CN100426545C

CN100426545C - Nitride semiconductor device

Info

Publication number: CN100426545C
Application number: CNB2006101322811A
Authority: CN
Inventors: 谷沢公二; 三谷友次; 中河義典; 高木宏典; 丸居宏充; 福田芳克; 池上武止
Original assignee: Nichia Chemical Industries Ltd
Current assignee: Nichia Chemical Industries Ltd
Priority date: 1998-03-12
Filing date: 1999-03-10
Publication date: 2008-10-15
Anticipated expiration: 2019-03-10
Also published as: CN100449808C; CN100536182C; CN1941436A; CN1933199A; CN1933201A; CN101188266B; CN1933200A; CN100446289C; CN101188266A

Abstract

A nitride semiconductor light emitting device comprising an active layer of multiple quantum well structure provided between an n-side region including a plurality of nitride semiconductor layers and a p-side region including a plurality of nitride semiconductor layers, having a light emission output improved by allowing the characteristics of the active layer to exhibit well, and capable of being applied to a wider range of various application products, wherein a multilayer film comprising two nitride layers is formed in at least one of the n- and p-side regions.

Description

Nitride semiconductor device

Technical field

The present invention relates at light-emitting component, photo-sensitive cells such as light-emitting diode (LED), laser diode, solar cell, optical sensors, or employed nitride-based semiconductor (for example, In in the electronic devices such as transistor, power supply apparatus _xAl _yGa _1-x-yN, 0≤x, 0≤y, x+y≤1) element.

Background technology

Nitride-based semiconductor has been applied in the various light sources such as panchromatic light-emitting diode display, traffic lights, image scanner light source as the material of high-brightness blue LED, pure green LED.These LED elements have substantially following each layer are stacked gradually structure on sapphire substrate: the resilient coating that is made of GaN, the n side contact layer that constitutes by the GaN of the Si that mixed, active layer with multi-quantum pit structure single quantum (SQW:Single-Quantum-Well) or that have InGaN (MQW:Multi-Quantum-Well) of InGaN, the p side coating layer that constitutes by the AlGaN of doped with Mg, the p side contact layer that constitutes by the GaN of doped with Mg; These elements also demonstrate very excellent performance, promptly, when electric current is 20mA, be that power is that 5mW, external quantum efficiency are 9.1% in the blue led of 450nm at emission wavelength, be that power is that 3mW, external quantum efficiency are 6.3% in the green LED of 520nm at emission wavelength.

Like this, what adopt in nitride semiconductor photogenerator is the dual heterostructure with active layer, and described active layer is to have the single quantum of the trap layer that is made of InGaN or the active layer of multi-quantum pit structure.

In addition, in nitride semiconductor photogenerator, because multi-quantum pit structure has the structure that is made of a plurality of little bands (mini band): the efficient height, even it is luminous that very little electric current also can be realized, so can expect to improve the raising of the element characteristic of luminous power output etc. by single quantum.

For example, LED element as the active layer that uses multi-quantum pit structure, open in the flat 10-135514 communique the spy and to disclose a kind of nitride semiconductor device, for the luminous efficiency that improves it and luminous intensity, described nitride semiconductor device has following each layer at least: the barrier layer that is made of the GaN of non-doping, the luminescent layer of the multi-quantum pit structure that the trap layer that is made of the InGaN of non-doping is formed, and then have the coating layer of the band gap also wideer (band gap) than the barrier layer of luminescent layer.

Yet when active layer was made multi-quantum pit structure, owing to compare with the active layer of single quantum, the film thickness of the integral body of active layer was thicker, and series resistance increases so have longitudinally, for example, and the tendency that Vf in the LED element (forward voltage) increases.

As might be, for example open and put down in writing the laser diode that a kind of p sidelight ducting layer, contact layer that will be more than active layer etc. be made the superlattice layer that contains the InAlGaN layer among the flat 9-298341 the spy as the technology that Vf is reduced.This technology is by p type nitride semiconductor layer is made the superlattice structure that contains the In nitride semiconductor layer, and described nitride semiconductor layer contains In, and the carrier concentration of p layer is increased, thereby reduces the technology of the threshold value of laser diode.Yet because the crystallinity of the nitride-based semiconductor of the such 4 yuan of mixed crystal of InAlGaN is very poor in the reality, and the nitride-based semiconductor that is difficult to contain In makes the p type, so in fact be difficult to produce LED element or LD element.

Therefore, improve luminous power output greatly, be difficult to give full play to desired possibility though can expect the active layer of this multi-quantum pit structure.

In addition, about the LD element, the applicant had once delivered and made a kind of nitride semiconductor Laser device that contains active layer on nitride semiconductor base plate, (ICNS gives the original text collection in ' 97 more than 10,000 hours to have reached for the first time under the room temperature continuous oscillation in the world, October 27-31,1997, P444-446; And Jpn.J.Appl.Phys.Vol.36 (1997) pp.L1568-1571 Part2, No.12A, on December 1st, 1997).

, for example, for the LED element is used in lighting source, by among outdoor display device of daylight direct irradiation etc., require the element that Vf further reduces and luminous efficiency is high.In addition, for the LD element is used in light sources such as optical pickup, must further reduce its threshold value, life-span etc. of improving it and further improve.

Nearest in addition, in using the light-emitting component of this nitride-based semiconductor, carried out following research, it is disclosed like that to open flat 8-97468 communique as the spy, uses the band-gap energy InGaN littler than GaN to form in the past p type contact layer with GaN formation p lateral electrode.That is,, reduce the potential barrier between p type contact layer and the p lateral electrode, to obtain good Ohmic contact by using the little InGaN of band-gap energy.

Yet InGaN is difficult to grow into the few and film of good crystallinity of defective, the ohmic contact with fully low contact resistance that very difficult acquisition is such as expected.In addition, also existence makes the contact resistance problem of unstable because of the crystallinity deviation of the InGaN layer that is generated.Therefore, very difficult fully low and stable operating voltage and the high-output power that obtain simultaneously of nitride semiconductor device in the past that has the p type contact layer of making by InGaN.Therefore, for example, when using the contact layer of being made by InGaN to constitute the LED element, there are the following problems, that is, the forward voltage during 20mA (Vf) can't hang down 3.4V～3.8V, and its deviation is also very big.

In addition and then, the element that is become by nitride system semiconductor even exist the possibility that also can worsen under the voltage of the 100V of the static that human body produced on its structure, should be noted that when handling.Therefore, in order further to improve the reliability of nitride semiconductor device, require further to improve the performance of its anti-electrostatic pressure.

Summary of the invention

The present invention puts forward in view of the above fact, and its purpose mainly is in the power output that improves nitride semiconductor devices such as LED, LD, reduces Vf, threshold value, to improve the luminous efficiency of element.Improve luminous efficiency and be with so that the efficient that also improves other electronic devices of use nitride-based semiconductor such as photo-sensitive cell link together.

In addition, the present invention also aims to: by using the active layer of multi-quantum pit structure, give full play to its characteristic,, enlarge the scope of application of the various application products of nitride semiconductor luminescent element in the hope of further improving luminous power output.

In addition, the present invention also aims to: a kind of nitride semiconductor device is provided, and described nitride semiconductor device can reduce the contact resistance of p lateral electrode and p type contact layer, can obtain high-output power under stable low-work voltage.

Further, the present invention also aims to provide a kind of and can improve luminous power output, and the well behaved nitride semiconductor luminescent element of anti-electrostatic pressure.

First nitride semiconductor device of the present invention reduces Vf and threshold value by following formation, and luminous efficiency is improved.

That is, first nitride semiconductor device of the present invention is in the territory, n lateral areas with nitride multilayer thing semiconductor layer and have the nitride semiconductor device that has active layer between the territory, p lateral areas of nitride multilayer thing semiconductor layer;

It is characterized in that, at least one deck nitride semiconductor layer in territory, said n lateral areas has the n side stratified film that first nitride semiconductor film that will contain In and second nitride semiconductor film that has with the different compositions of this first nitride semiconductor film are laminated, and at least one side's thickness exists in above-mentioned first nitride semiconductor film or above-mentioned second nitride semiconductor film

Or below.

In first nitride semiconductor device of the present invention, preferred above-mentioned first nitride semiconductor film and second nitride semiconductor film the two be

Or below, be more preferably

Or below, most preferably be

Or below.Because by reducing thickness in this wise, stratified film forms superlattice structure, can improve the crystallinity of stratified film, therefore can improve its power output.In addition, active layer is preferably the nitride-based semiconductor that contains In at least, is preferably single quantum or multi-quantum pit structure with the trap layer that is made of InGaN.

In addition, in first nitride semiconductor device of the present invention, first nitride semiconductor film is In _xGa _1-xN (0＜x＜1), second nitride semiconductor film is In _yGa _1-yN (0≤y＜1, Y＜X), most preferably be GaN.

Further, in first nitride semiconductor device of the present invention, the thickness of at least one side in above-mentioned first nitride semiconductor film or above-mentioned second nitride semiconductor film can for, between the first adjoining nitride semiconductor film or different between the second adjoining nitride semiconductor film.Promptly, under the situation that forms the stratified film that first nitride semiconductor film or second nitride semiconductor film is multilayer laminated, the thickness that clips two-layer first nitride semiconductor film (second nitride semiconductor film) of second nitride semiconductor film (first nitride semiconductor film) can be different.

And then in addition, in first nitride semiconductor device of the present invention, the composition of the III family element of at least one side in above-mentioned first nitride semiconductor film or above-mentioned second nitride semiconductor film can for, different between the composition of the identical III of the first adjoining nitride semiconductor film or adjoining second nitride semiconductor film family element.Promptly, under the situation that forms the stratified film that first nitride semiconductor film or second nitride semiconductor film is multilayer laminated, the ratio of composition of III family element that clips two-layer first nitride semiconductor film (second nitride semiconductor film) of second nitride semiconductor film (first nitride semiconductor film) can be different.

In addition, in first nitride semiconductor device of the present invention, n side stratified film can separate with active layer and form, but in order further to improve power output, preferably forms in the mode of joining with active layer.

In addition, in first nitride semiconductor device of the present invention, first nitride semiconductor film and second nitride semiconductor film also can be non-doping.Here, so-called non-doping refers to the state of the impurity that undopes wittingly, for example, from the impurity that adjacent nitride semiconductor layer is sneaked into, also is called non-doping owing to spread in the present invention.In addition owing to the concentration of the diffusion impurity of sneaking into distribution gradient mostly in each layer.

In addition, in first nitride semiconductor device of the present invention, also can be in any one party of first nitride semiconductor film or second nitride semiconductor film Doped n-type impurity.This doping is called modulation doping, by modulation doping, can improve power output.As n type impurity, can select to use IV family, VI family elements such as Si, Ge, Sn, S in addition, preferably use Si, Sn.

In addition, in first nitride semiconductor device of the present invention, also can be in both of first nitride semiconductor film and second nitride semiconductor film Doped n-type impurity all.When Doped n-type impurity, the concentration of impurity is adjusted at 5 * 10 ²¹/ cm ³Or below, be preferably 1 * 10 ²⁰/ cm ³Or below.If be higher than 5 * 10 ²¹/ cm ³, the crystallinity of nitride semiconductor layer will worsen, and has the tendency that power output descends on the contrary.Also identical under the situation of modulation doping.

And then, in first nitride semiconductor device of the present invention, nitride semiconductor layer as territory, above-mentioned p lateral areas, have the 3rd nitride semiconductor film that will contain Al with having stacked with the tetrazotization thing semiconductor film of the different compositions of the 3rd nitride-based semiconductor p side stratified film that form, and the thickness of at least one side in preferred above-mentioned the 3rd nitride semiconductor film or the above-mentioned tetrazotization thing semiconductor layer exists

Or below.In addition, in the present invention, and then preferred the 3rd nitride semiconductor film and tetrazotization thing semiconductor film both exist

Or below, and then preferably exist

Or below, most preferably be

Or below.Because by making the thickness attenuate like this, stratified film can become superlattice structure, the crystallinity of stratified film makes moderate progress, and therefore can improve power output.

In addition and then, in first nitride semiconductor device of the present invention, the 3rd nitride semiconductor film is preferably Al _aGa _1-aN (0＜a≤1), above-mentioned tetrazotization thing semiconductor film is preferably In _bGa _1-bN (0≤b＜1, b＜a), and then preferred above-mentioned tetrazotization thing semiconductor film is GaN.

In addition, in first nitride semiconductor device of the present invention, the thickness of at least one side in above-mentioned the 3rd nitride semiconductor film or the above-mentioned tetrazotization thing semiconductor film can for, between the 3rd adjoining nitride semiconductor film or different between the adjoining tetrazotization thing semiconductor film.Promptly, using multilayer the 3rd nitride semiconductor film or multilayer second nitride semiconductor film to come under the stacked situation respectively, the thickness that clips the tetrazotization thing semiconductor film (the 3rd nitride semiconductor film) of the 3rd nitride semiconductor film (tetrazotization thing semiconductor film) also can be different.

And then, in first nitride semiconductor device of the present invention, the composition of the III family element of at least one side's film in above-mentioned the 3rd nitride semiconductor film or the above-mentioned tetrazotization thing semiconductor film can for, different between the composition of the identical III of the 3rd adjoining nitride semiconductor film or adjoining tetrazotization thing semiconductor film family element.Promptly, under the situation that forms the stratified film that the 3rd nitride semiconductor film or tetrazotization thing semiconductor film is multilayer laminated, the proportion of composing of III family element that clips the tetrazotization thing semiconductor film (the 3rd nitride semiconductor film) of the 3rd nitride semiconductor film (tetrazotization thing semiconductor film) also can be different.

In addition and then, in first nitride semiconductor device of the present invention, p side stratified film is the same with n side stratified film, can separate formation with active layer, but preferred and active layer joins and forms.Form by joining with active layer in this wise, can improve power output.

In addition, in first nitride semiconductor device of the present invention, the 3rd nitride semiconductor film and tetrazotization thing semiconductor film also can be non-doping.When the stratified film of p side being made non-doping rete, preferably its thickness is made 0.1 μ m or following.As thicker than 0.1 μ m, will make the hole be difficult to inject active layer, have the tendency that power output is descended.In addition, about the definition of non-doping, identical with n side stratified film.

In addition, in first nitride semiconductor device of the present invention, among in the 3rd nitride semiconductor film or tetrazotization thing semiconductor film either party, can doped p type impurity.By modulation doping in this wise, have the tendency that power output is improved.As p type impurity, II family elements such as Mg, Zn, Cd, Be, Ca be can select in addition, Mg, Be preferably used.

In addition, in first nitride semiconductor device of the present invention, also can be in the 3rd nitride semiconductor film and tetrazotization thing semiconductor film doped p type impurity all.When doped p type impurity, the concentration of impurity is adjusted at 1 * 10 ²²/ cm ³Or below, be preferably 5 * 10 ²⁰/ cm ³Or below.If be higher than 1 * 10 ²²/ cm ³, the crystallinity of nitride semiconductor layer will worsen, and has the tendency that power output is reduced.This is also identical under the situation of modulation doping.

Second～the 5th nitride semiconductor device of the present invention be by following formation improve the nitride semiconductor device of the active layer that has adopted multi-quantum pit structure luminous power output, enlarge the nitride semiconductor device of the scope of application of the application product of nitride semiconductor device.

That is, second nitride semiconductor film of the present invention is in the territory, n lateral areas with nitride multilayer thing semiconductor layer and has the nitride semiconductor device that has active layer between the territory, p lateral areas of nitride multilayer thing semiconductor layer, it is characterized in that:

At least one deck nitride semiconductor layer in territory, said n lateral areas is that at least two kinds of nitride semiconductor films is stacked and n side first stratified film that form, described at least two kinds of nitride semiconductor films are with different doped in concentrations profiled n type impurity, and have mutually different band-gap energy;

At least one deck nitride semiconductor layer in territory, above-mentioned p lateral areas is that third and fourth nitride semiconductor film is stacked and p side multilayer film coating layer that form, described third and fourth nitride semiconductor film is doped p type impurity and forming respectively, and band-gap energy is different;

Above-mentioned active layer is by In _aGa _1-aThe multi-quantum pit structure that N (0≤a＜1) constitutes.

In addition, the 3rd nitride semiconductor device of the present invention is in the territory, n lateral areas with nitride multilayer thing semiconductor layer and has the nitride semiconductor device that has active layer between the territory, p lateral areas of nitride multilayer thing semiconductor layer, it is characterized in that:

At least one deck nitride semiconductor layer in territory, said n lateral areas is that at least two kinds of nitride semiconductor films is stacked and n side first stratified film that form, and described at least two kinds of nitride semiconductor films have same composition with variable concentrations Doped n-type impurity;

In addition, in the of the present invention second and the 3rd nitride semiconductor device, the concentration of the concentration of the p type impurity of above-mentioned the 3rd nitride semiconductor film and the p type impurity of above-mentioned tetrazotization thing semiconductor film both can be different, also can be identical.

In addition, tetrazotization thing semiconductor element of the present invention is in the territory, n lateral areas with nitride multilayer thing semiconductor layer and has the nitride semiconductor device that has active layer between the territory, p lateral areas of nitride multilayer thing semiconductor layer, it is characterized in that:

At least one deck nitride semiconductor layer in territory, said n lateral areas is that at least two kinds of nitride semiconductor films is stacked and n side first stratified film that form, and described at least two kinds of nitride semiconductor films have the identical composition that is doped with n type impurity with variable concentrations;

At least one deck nitride semiconductor layer in territory, above-mentioned p lateral areas is by the Al that contains p type impurity _bGa _1-bThe p side monofilm coating layer that N (0≤b≤1) is constituted;

In addition, the 3rd or tetrazotization thing semiconductor element in, first stratified film of preferred said n side is laminated by two kinds of nitride semiconductor films, described two kinds of nitride semiconductor films are made of GaN respectively, with mutually different doped in concentrations profiled n type impurity are arranged.

And then the 5th nitride semiconductor device of the present invention is in the territory, n lateral areas with nitride multilayer thing semiconductor layer and has the nitride semiconductor device that has active layer between the territory, p lateral areas of nitride multilayer thing semiconductor layer, it is characterized in that:

At least one deck nitride semiconductor layer in territory, said n lateral areas is that at least two kinds of nitride semiconductor films is stacked and n side first stratified film that form, described at least two kinds of nitride semiconductor films have n type impurity with different doped in concentrations profiled, and band-gap energy also has nothing in common with each other;

In addition, in second～the 5th nitride semiconductor device, preferably between said n side first stratified film and active layer, have n side second stratified film, described n side second stratified film by first nitride semiconductor film that contains In with have different second nitride semiconductor films of forming and be laminated with this first nitride semiconductor film.

And then, in second～the 5th nitride semiconductor device, in territory, said n lateral areas, also can form the n side contact layer that contains n type impurity than more close substrate one side of first stratified film of said n side.

In addition and then, in second～the 5th nitride semiconductor device, preferred said n side contact layer be formed on non-doping the GaN layer above.

In addition, in second～the 5th nitride semiconductor device, the GaN layer of preferred above-mentioned non-doping is formed on the Ga by low-temperature epitaxy _dAl _1-dOn the resilient coating that N (0＜d≤1) is constituted, further, can also form p side GaN contact layer on the monofilm coating layer of the multilayer film coating layer of above-mentioned p side or p side, described p side GaN contact layer contains the Mg as p type impurity.

That is, second～the 5th nitride semiconductor device of the present invention, be with the luminescent layer that clips multi-quantum pit structure mode, with n side first stratified film and p side multilayer film coating layer or the combination of p side monofilm coating layer and form, thereby improve luminous efficiency.Wherein, described n side first stratified film is made of n type impurity concentration different two kinds or above nitride semiconductor layer in the n side, described p side multilayer film coating layer is made of third and fourth nitride semiconductor film in the p side, and described p side monofilm coating layer contains p type impurity, is by Al _bGa _1-bN (0≤b≤1) is constituted.

Combine by the nitride multilayer thing semiconductor layer that will have specific composition, structure etc. like this, just can bring into play the performance of the active layer of multi-quantum pit structure efficiently.In addition, put down in writing below with the combination of the active layer of multi-quantum pit structure in preferred other nitride semiconductor layer.

In second～the 5th nitride semiconductor device of the present invention, if between said n side first stratified film and active layer, have first nitride semiconductor film that will contain In and have n side second stratified film stacked with second nitride semiconductor film of the different compositions of this first nitride semiconductor film, then can further improve luminous efficiency, Vf is reduced, and improve luminous efficiency.

And then, in second～the 5th nitride semiconductor device of the present invention,, just can improve luminous power output, but also can reduce Vf if form the n side contact layer that contains n type impurity in more close substrate one side than said n side first stratified film.

In addition and then, in second～the 5th nitride semiconductor device of the present invention, if the said n side contact layer is to form on the GaN of non-doping layer, then the GaN layer of this non-doping can be used as the good layer of crystallinity and obtains, therefore can improve crystallinity as the n side contact layer of the layer that forms the n electrode, also the crystallinity that is formed on other nitride semiconductor layers such as active layer on the n side contact layer can be improved, therefore luminous power output can be further improved.

In addition and then, in second～the 5th nitride semiconductor device of the present invention, if the GaN layer of above-mentioned non-doping is formed on the G by low-temperature epitaxy _aDAl _1-dOn the resilient coating that N (0＜d≤1) is constituted, just can further improve the crystallinity of the GaN layer of non-doping, also can further improve the crystallinity of n side contact layer etc., therefore can further improve luminous power output; And then in addition, if on above-mentioned p side multilayer film coating layer or p side monofilm coating layer, form the p side GaN contact layer of doped with Mg, then can obtain good p type electric conductivity, simultaneously, have good Ohmic contact between this p side GaN contact layer and the formation p electrode thereon, can further improve luminous power output.

In addition, the 6th nitride semiconductor device of the present invention is finished having found following true back, promptly, make superlattice structure by the p type contact layer that will contain In, can form that a kind of defective is few, the p type contact layer of good crystallinity, it provides a kind of nitride semiconductor device that can obtain stable high-output power under low operating voltage.

Promptly, the 6th nitride semiconductor device of the present invention, be in territory, p lateral areas and comprise the nitride semiconductor device that possesses active layer between the territory, n lateral areas of nitride multilayer thing semiconductor layer, it is characterized in that with the nitride multilayer thing semiconductor layer that contains p type contact layer:

Above-mentioned p type contact layer has the film that will contain the first and second different nitride semiconductor films of mutual composition and stacks gradually the superlattice structure that forms, and in above-mentioned two kinds of nitride semiconductor films, at least the first nitride semiconductor film contains In.

Thus, just can reduce the contact resistance of p lateral electrode and p type contact layer, can under stable low operating voltage, obtain high power output.

In addition, in the 6th nitride semiconductor device of the present invention, preferably between above-mentioned first nitride semiconductor film and above-mentioned second nitride semiconductor film, form and form continually varying composition graded bedding, described composition gradual change is the composition that changes to above-mentioned second nitride semiconductor film from the composition of above-mentioned first nitride semiconductor film, thus, just can further improve the crystallinity of p type contact layer.

In addition, in the 6th nitride semiconductor device of the present invention, preferably the In that contains with above-mentioned first nitride semiconductor film measures the In amount that the contains height that is set at than above-mentioned second nitride semiconductor film.Like this, can further reduce the resistance of p type contact layer.

In addition, in the 6th nitride semiconductor device of the present invention, when one of in above-mentioned two kinds of nitride semiconductor layers when containing the In layer, a preferred side's above-mentioned first nitride semiconductor film is by In _xGa _1-xThe layer that N constitutes, the opposing party's second nitride semiconductor film is by Al _yGa _1-yThe layer that N constitutes.

And then, in the 6th nitride semiconductor device of the present invention, also can be at any one party doped p type impurity in above-mentioned first nitride semiconductor film and above-mentioned second nitride semiconductor film, at the opposing party's p type impurity that then undopes.

In addition, in the 6th nitride semiconductor device of the present invention, under the situation of above-mentioned first and second nitride semiconductor films difference doped p type impurity, preferably in a side nitride semiconductor layer, mix 1 * 10 ¹⁹/ cm ³～5 * 10 ²¹/ cm ³The p type impurity of scope, in the opposing party's nitride semiconductor layer, mix 5 * 10 ¹⁸/ cm ³～5 * 10 ¹⁹/ cm ³Scope and also than the p type impurity of an above-mentioned side's nitride semiconductor layer doping less amount.

In addition, in the 6th nitride semiconductor device of the present invention, preferred above-mentioned first nitride semiconductor film is in the most surperficial formation, and the p lateral electrode be formed on above-mentioned this most surperficial nitride semiconductor layer and form with joining.In addition, at this moment, the concentration of p type impurity that preferably makes above-mentioned first nitride semiconductor film is greater than the p type impurity concentration in above-mentioned second nitride semiconductor film.

And then, in the 6th nitride semiconductor device of the present invention, also can between above-mentioned active layer and above-mentioned p type contact layer, have the p type coating layer that constitutes by the nitride-based semiconductor that contains Al.

In the 6th nitride semiconductor device of the present invention, preferred above-mentioned P type coating layer has by Al _xGa _1-xN (0＜x≤1) constituted the layer and by In _yGa _1-yThe layer that N (0≤y＜1) is constituted is the alternately laminated superlattice structure that forms mutually.

As mentioned above, the 6th nitride semiconductor device of the present invention has the alternately laminated superlattice structure that forms of first and second nitride semiconductor films that composition is had nothing in common with each other, in above-mentioned two kinds of nitride semiconductor layers, at least the first nitride semiconductor film has the p type contact layer that contains In.Thus, just can form the few and p type contact layer of good crystallinity of defective, owing to can reduce the resistance value of p type contact layer itself, and can do the contact resistance of p lateral electrode and p type contact layer very little, so can under stable low-work voltage, obtain high power output.

In addition, the the of the present invention the 7th and the 8th nitride semiconductor device is by following formation, can improve the luminous power output of the nitride semiconductor device of the active layer that has used multi-quantum pit structure, and make anti-electrostatic pressure functional, enlarged the range of application of the nitride semiconductor device of the active layer that has adopted multi-quantum pit structure.

That is, the 7th nitride semiconductor device of the present invention is in the territory, n lateral areas with nitride multilayer thing semiconductor layer and has the nitride semiconductor device that has active layer between the territory, p lateral areas of nitride multilayer thing semiconductor layer, it is characterized in that:

At least one deck nitride semiconductor layer in territory, said n lateral areas is to stack gradually n side first stratified film that forms with at least three layers, described at least three layers are respectively: the lower floor that is made of the nitride semiconductor film of non-doping, the intermediate layer that constitutes by the nitride semiconductor film of the n type impurity that mixed, and the upper strata that constitutes by the nitride semiconductor film of non-doping;

At least one deck nitride semiconductor layer in territory, above-mentioned p lateral areas is the p side multilayer film coating layer that is laminated by third and fourth nitride semiconductor film, described third and fourth nitride semiconductor film p type impurity that mixed respectively, and band-gap energy is different;

In addition, in the 7th nitride semiconductor device of the present invention, the concentration of the concentration of the p type impurity of above-mentioned the 3rd nitride semiconductor film and the p type impurity of above-mentioned tetrazotization thing semiconductor film can be different, also can be identical.

In addition, the 8th nitride semiconductor device of the present invention is a kind of in the territory, n lateral areas with nitride multilayer thing semiconductor layer and have the nitride semiconductor device that has active layer between the territory, p lateral areas of nitride multilayer thing semiconductor layer, it is characterized in that:

At least one deck nitride semiconductor layer in territory, said n lateral areas is to stack gradually n side first stratified film that forms with at least three layers, described at least three layers are respectively: the lower floor that is made of the nitride-based semiconductor of non-doping, the intermediate layer that constitutes by the nitride-based semiconductor of the n type impurity that mixed, and the upper strata that constitutes by the nitride-based semiconductor of non-doping;

Above-mentioned active layer is to contain In _aGa _1-aThe multi-quantum pit structure of N (0≤a＜1).

And then, in the of the present invention the 7th and the 8th nitride semiconductor device, it is characterized in that said n side first stratified film comprises: by thickness be

The lower floor that constitutes of the nitride-based semiconductor of non-doping, by thickness be

Doping the intermediate layer that constitutes of the nitride-based semiconductor of n type impurity, and be by thickness

The upper strata that constitutes of the nitride-based semiconductor of non-doping.

In the of the present invention the 7th and the 8th nitride semiconductor device, preferably between said n side first stratified film and active layer, have first nitride semiconductor film that to contain In and have n side second stratified film that is laminated with second nitride semiconductor film of the different compositions of this first nitride semiconductor film.

In addition and then, in the of the present invention the 7th and the 8th nitride semiconductor device, also can on said n side nitride semiconductor layer, have the n side contact layer that contains n type impurity in a side than the more close substrate of said n side first stratified film (modulation doping).

In the of the present invention the 7th and the 8th nitride semiconductor device, preferred said n side contact layer be formed on non-doping the GaN layer above.

In addition, in the of the present invention the 7th and the 8th nitride semiconductor device, in above-mentioned nitride semiconductor device, the GaN layer of above-mentioned non-doping is formed on the Ga that grows up by low temperature _dAl _1-dOn the resilient coating that N (0＜d≤1) is constituted, and then also can on above-mentioned p side multilayer film coating layer or p side monofilm coating layer, form the p side GaN contact layer that contains as the Mg of p type impurity.

Promptly, in the of the present invention the 7th and the 8th nitride semiconductor device, mode with the active layer that clips multi-quantum pit structure, with n side first stratified film and p side multilayer film coating layer or the combination of p side monofilm coating layer and form, thereby can improve luminous efficiency, to obtain luminous power output good, and the good nitride semiconductor device of electrostatic withstand voltage.Wherein, described n side first stratified film is that these the specific layer structures of upper strata by the intermediate layer of the lower floor of non-doping in the territory, n lateral areas, Doped n-type impurity and non-doping are constituted, described p side multilayer film coating layer is made of third and fourth nitride semiconductor film in territory, p lateral areas, and described p side monofilm coating layer contains p type impurity by Al _bGa _1-bN (0≤b≤1) constitutes.

Combine by the nitride multilayer thing semiconductor layer that will have specific composition, laminated construction in this wise, just can bring into play the performance of the active layer of multi-quantum pit structure expeditiously, can also improve anti-electrostatic pressure performance simultaneously.

And then the thickness of the present invention's each layer by will constituting n side first stratified film is made as the combination of specific scope, can further improve anti-electrostatic pressure performance when obtaining good luminous power output.

In addition, in the present invention, so-called non-doping is meant not to be specially impurity and the layer that forms, even diffusion impurity from adjacent layer, sneak into the layer of impurity by the pollution that comes from raw material or device, so long as be not specially during impurity, can be with it as non-doped layer.In addition, the impurity of sneaking into owing to diffusion makes the situation of impurity concentration distribution gradient sometimes in layer.

In addition, with the combination of the active layer of multi-quantum pit structure in, preferably other nitride semiconductor layer is as described below.

In the present invention,, then can further improve luminous efficiency, can also reduce the voltage (hereinafter being called Vf) of positive direction simultaneously, improve luminous efficiency if between said n side first stratified film and active layer, have n side second stratified film.Wherein, described n side second stratified film is that first nitride semiconductor film that will contain In is laminated with second nitride semiconductor film that has with the different compositions of this first nitride semiconductor film.

And then, in the present invention,, just can improve luminous power output if having the n side contact layer that contains n type impurity in a side than the more close substrate of said n side first stratified film, reduce Vf.

In addition and then, in the present invention, if on the GaN of non-doping layer, form the said n side contact layer, then can obtain GaN layer as the good non-doping of crystallinity, thereby can improve crystallinity as the n side contact layer of the layer that forms the n electrode, also can improve other the crystallinity of nitride semiconductor layer of on the n side contact layer formed active layer etc., can also improve luminous power output.

In addition and then, in the present invention, if the GaN layer of above-mentioned non-doping is formed on the Ga that grows up by low temperature _dAl _1-dOn the resilient coating that N (0＜d≤1) is constituted, just can further improve the crystallinity of the GaN layer of non-doping, the crystallinity of n side contact layer etc. also can be improved further, and can realize the further raising of luminous power output.And then in addition, if owing on the monofilm coating layer of p side multilayer film coating layer or p side, be formed with the p side GaN contact layer of the Mg that mixed, then can obtain good p type characteristic at an easy rate, can also obtain p side GaN contact layer and be formed on the good Ohmic contact of the p electrode above it, thereby can further improve luminous power output.

In addition, the the 9th～the 11 nitride semiconductor device of the present invention, has stratified film respectively in territory, n lateral areas and territory, p lateral areas, the stratified film by making territory, n lateral areas and the stratified film in territory, p lateral areas form or the number of plies aspect be asymmetrical, just can improve luminous power output and anti-electrostatic pressure performance, and can reduce Vf, enlarge the scope of application of various application products.

That is, the 9th nitride semiconductor device of the present invention is in the territory, n lateral areas with nitride multilayer thing semiconductor layer and has the nitride semiconductor device that has active layer between the territory, p lateral areas of nitride multilayer thing semiconductor layer, it is characterized in that:

At least one deck nitride semiconductor layer in territory, said n lateral areas is by the stacked n type stratified film that forms of nitride multilayer thing semiconductor film;

At least one deck nitride semiconductor layer in territory, above-mentioned p lateral areas is by the stacked p type stratified film that forms of nitride multilayer thing semiconductor film; And

The composition that constitutes said n type stratified film is different with the composition that constitutes p type stratified film.

In addition, the tenth nitride semiconductor device of the present invention is in the territory, n lateral areas with nitride multilayer thing semiconductor layer and has the nitride semiconductor device that has active layer between the territory, p lateral areas of nitride multilayer thing semiconductor layer, it is characterized in that:

The stacked number of plies of the nitride semiconductor film of formation said n type stratified film is different with the stacked number of plies of the nitride semiconductor film that constitutes p type stratified film.

And then the of the present invention the 11 nitride semiconductor device is in the territory, n lateral areas with nitride multilayer thing semiconductor layer and has the nitride semiconductor device that has active layer between the territory, p lateral areas of nitride multilayer thing semiconductor layer, it is characterized in that:

The composition that constitutes said n type stratified film is different with the composition that constitutes p type stratified film, and the stacked number of plies of the nitride semiconductor film of formation said n type stratified film is different with the stacked number of plies of the nitride semiconductor film that constitutes p type stratified film.

In addition, in the 9th～the 11 nitride semiconductor device of the present invention, the number of plies that preferably constitutes the nitride semiconductor layer of above-mentioned p type stratified film is lacked than the number of plies of the nitride semiconductor layer that constitutes n type stratified film.

In addition, in the 9th～the 11 nitride semiconductor device of the present invention, preferred said n type stratified film contains Al _zGa _1-zN (0≤z＜1) and In _pGa _1-pN (0＜P＜1), above-mentioned p type stratified film contains Al _xGa _1-xN (0＜x＜1=and In _yGa _1-yN (0≤y＜1).

And then the 9th～the 11 nitride semiconductor device of the present invention preferably carries out modulation doping with above-mentioned p type stratified film and/or n type stratified film.

Promptly, the the 9th～the 11 nitride semiconductor device of the present invention, as mentioned above, by to clip the mode of active layer, form composition and/or different n type stratified film and the p type stratified films of the number of plies with the n type with the p type, and near the formation of the layer the active layer of component construction is specific, therefore can provide can improve luminous power output, reduce Vf, nitride semiconductor device that anti-electrostatic pressure is good.

The possibility that the active layer of quantum well structure will improve luminous power output stashes, so in element in the past, be difficult to the possibility of quantum well structure is performed to the degree that fully satisfies.

With respect to this, inventors of the present invention are that the performance of giving full play to the active layer of quantum well structure has been carried out various researchs, the result, by join with active layer or approaching, form to form and/or the number of plies mutually different n type stratified film and p type stratified film, in the performance of bringing into play active layer well, when realizing the raising of luminous power output, the reduction of Vf and the raising of anti-electrostatic pressure ability have also been realized.

Though reason is so not definite, but can think, may be to have improved crystallinity owing to forming multilayer film, add the crystallinity of improving active layer, the crystallinity that forms the layer of p electrode, and then, owing to forming and/or the difference of the crystallographic property of different n type stratified films that cause of the number of plies and p type stratified film acts on synergistically, whole element all there is good influence, so improved the performance (luminous power output, Vf, anti-electrostatic pressure performance etc.) of element.

In the 9th～the 11 nitride semiconductor device of the present invention, so-called stratified film, be stacked at least two-layer or above and form with forming different at least two kinds or above individual layer nitride semiconductor layers, form different modes with adjacent individual layer nitride semiconductor layer between mutually, stacked multilayer individual layer nitride semiconductor layer forms.

In addition, in the 9th～the 11 nitride semiconductor device of the present invention, the composition of the nitride-based semiconductor of the so-called n of formation type stratified film is different with the composition of the nitride-based semiconductor that constitutes p type stratified film, the meaning be constitute the composition of the individual layer nitride-based semiconductor of stratified film separately also can be identical, but the formation (all forming) of whole retes of the stratified film that multilayer individual layer nitride semiconductor layer is laminated is inconsistent.That is, so-called n type stratified film and p type stratified film, the composition that constitutes them also can be partly consistent, but the composition of each nitride semiconductor layer will be adjusted into not quite identical.

For example, so-called form differently, can enumerate different situations such as the ratio of the element (for example, the kind of the element of binary mixed crystal, ternary mixed crystal) that constitutes nitride-based semiconductor, element or band-gap energy.In addition, in stratified film, these values all are whole mean value.

In addition, in the present invention, so-called stacked number of plies difference is meant, as long as either party of p type or n type, the nitride-based semiconductor that constitutes stratified film is by many gather into folds layer by layer just passable more than one deck at least.

And then, in the 9th～the 11 nitride semiconductor device of the present invention, the preferred number of plies that constitutes the nitride semiconductor layer of p type stratified film, the number of plies than the nitride semiconductor layer that constitutes n type stratified film is lacked, this is because luminous power output, Vf and anti-electrostatic pressure characteristic can be improved, so preferred.

In addition and then, in the 9th～the 11 nitride semiconductor device of the present invention, the number of plies of the lamination of p type stratified film is as long as lack one deck at least than the stacked number of plies of n type stratified film.

And then the 9th～the 11 nitride semiconductor device of the present invention, contain Al by making n type stratified film _zGa _1-zN (0≤z＜1) and In _pGa _1-pN (0＜p＜1), make p type stratified film contain Al _xGa _1-xN (0＜x＜1) and In _yGa _1-yN (0≤y＜1) can obtain higher luminous power output, Vf and anti-electrostatic pressure performance.

In addition and then, the 9th～the 11 nitride semiconductor device of the present invention if p type stratified film and/or n type stratified film are carried out modulation doping, just can improve luminous power output, Vf and anti-electrostatic pressure performance.

In addition, in the 9th～the 11 nitride semiconductor device of the present invention, so-called modulation doping, refer in the individual layer nitride semiconductor layer that forms stratified film, make the impurity concentration difference in each adjacent nitride semiconductor layer, can make and constitute the adjacent side's nitride semiconductor layer of the stratified film impurity that undopes, the opposing party is impurity then, in addition, all during impurity, also can make the impurity concentration difference in each adjacent nitride semiconductor layer at two adjacent sides nitride semiconductor layer.

In addition, in the 9th～the 11 nitride semiconductor device of the present invention, when the composition of n type stratified film and p type stratified film not simultaneously, constitute the number of plies of n type stratified film and the number of plies of formation p type stratified film, both can be identical, also can be different, be preferably number of plies difference, the number of plies that is more preferably p type stratified film is less than the number of plies of n type stratified film, and this is being preferred aspect luminous power output, Vf and the anti-electrostatic pressure performance.

In addition, in the present invention, when the number of plies of n type stratified film and p type stratified film not simultaneously, the composition of the composition of n type stratified film and p type stratified film both can be identical, also can be different, be preferably and form differently, this is preferred obtaining aspect such as mentioned above effect of the present invention.

In addition, in the present invention, when the number of plies of n type stratified film and p type stratified film not simultaneously, for the not special restriction of the combination of the number of plies of n type and p type, so long as p type stratified film is different with the number of plies of n type stratified film, any combination can, preferably, as mentioned above, the number of plies of p type stratified film is lacked than the number of plies of n type stratified film, this obtain the invention described above effect aspect be preferred.

Description of drawings

Fig. 1 is the constructed profile of formation of the nitride semiconductor device (LED element) of expression embodiment of the present invention 1.

Fig. 2 is the constructed profile of formation of the LED element of expression embodiments of the invention 2.

Fig. 3 is the stereogram of formation of the nitride semiconductor luminescent element (LD element) of expression embodiments of the invention 16.

Fig. 4 is the constructed profile of structure of the nitride semiconductor device (LED element) of expression embodiment of the present invention 2.

Fig. 5 is the constructed profile of formation of the nitride semiconductor luminescent element of expression embodiment of the present invention 3.

Fig. 6 A is the constructed profile of formation of P side contact layer of the nitride semiconductor luminescent element of expression embodiment of the present invention 4.

Fig. 6 B is the curve chart of composition that schematically illustrates the In of Fig. 6 A.

Fig. 7 is the curve chart of expression multilayer film of the present invention (p side contact layer) with respect to the absorptivity of wavelength.

Fig. 8 is the constructed profile of formation of the nitride semiconductor device (LED element) of expression embodiment of the present invention 5.

Fig. 9 A is with respect to the curve chart of the relative value of the P0 of the thickness of the upper strata 305c of non-doping and Vf in the expression embodiment 5.

Fig. 9 B is with respect to the curve chart of the relative value of the anti-electrostatic pressure performance of the thickness of the upper strata 305c of non-doping in the expression embodiment 5.

Figure 10 A is with respect to the curve chart of the relative value of the P0 of the thickness of intermediate layer 305b and Vf in the expression embodiment 5.

Figure 10 B is with respect to the curve chart of the relative value of the anti-electrostatic pressure performance of the thickness of intermediate layer 305b in the expression embodiment 5.

Figure 11 A is with respect to the curve chart of the relative value of the P0 of the thickness of the 305a of lower floor of non-doping and Vf in the expression embodiment 5.

Figure 11 B is with respect to the curve chart of the relative value of the anti-electrostatic pressure performance of the thickness of the upper strata 305a of non-doping in the expression embodiment 5.

Embodiment

Below, describe being used to implement the preferred embodiments of the invention with reference to accompanying drawing.

Embodiment 1

Fig. 1 is the constructed profile of formation of the nitride semiconductor device (LED element) of expression embodiment of the present invention 1.This LED element has the structure that has stacked gradually following each layer on sapphire substrate 1: first resilient coating 2 that is made of GaN; Second resilient coating 3 that constitutes by the GaN of non-doping; The n side contact layer 4 that constitutes by the GaN of the Si that mixed; The three buffer layer 5 that constitutes by the GaN layer of non-doping; The n side stratified film 6 that constitutes by the InGaN/GaN superlattice structure; The active layer 7 of the multi-quantum pit structure that constitutes by InGaN/GaN; The p side stratified film 8 that constitutes by the AlGaN/GaN superlattice structure; The p side contact layer 9 that constitutes by the GaN of the Mg that mixed.

Promptly, the LED element of embodiment 1 is, on sapphire substrate 1, be folded with by territory, n lateral areas 30 and territory, p lateral areas that the active layer 7 of multi-quantum pit structure forms, territory, described n lateral areas 30 is made of first resilient coating 2, second resilient coating 3, n side contact layer 4, three buffer layer 5 and n side stratified film 6, and territory, described p lateral areas is made of p side stratified film 8 and p side contact layer 9.

As shown in Figure 1, in the nitride semiconductor device of the present embodiment 1, clipping active layer 7 and be arranged in the territory, n lateral areas 30 of bottom, having the first nitride semiconductor film 6a that to contain In and have the n side stratified film 6 that is laminated with the second nitride semiconductor film 6b of the different compositions of this first nitride semiconductor film 6a.In n side stratified film 6, preferably form one deck or the above first nitride semiconductor film 6a and the second nitride semiconductor film 6b at least respectively, add up to 3 layers or more than, and then preferred stacked at least respectively 2 layers or more than, add up to stacked 4 layers or more than.Join and under the situation about forming at n side stratified film 6 and active layer 7, the stratified film that joins with initial one deck (trap layer or barrier layer) of active layer both can be the first nitride semiconductor film 6a, can be the second nitride semiconductor film 6b, the lamination order of n side stratified film need to be particularly limited yet.In addition, in Fig. 1,, in the present embodiment 1, also can between this stratified film 6 and active layer 7, have the layer that constitutes by other n type nitride-based semiconductors though n side stratified film 6 joins with active layer 7 and forms.In addition, because by making the first nitride semiconductor film 6a that constitutes this n side stratified film 6 or the thickness of at least one side among the second nitride semiconductor film 6b be

Or following, be preferably

Or following, most preferably be

Or below, the thickness of thin layer is in elasticity critical film thickness or following, and crystallinity is improved, and stacked thereon the crystallinity of first or second nitride semiconductor film also can improve, so can improve the crystallinity of stratified film integral body, improve the power output of element.

The first nitride semiconductor film 6a is the nitride-based semiconductor that contains In, is preferably the In of ternary mixed crystal _xGa _1-xN (0＜x＜1), and then to be preferably the x value be 0.5 or following In _xGa _1-xN most preferably is the x value and is 0.1 or following In _xGa _1-xN.On the other hand, the second nitride semiconductor film 6b is so long as form the nitride semiconductor film different with the first nitride semiconductor film 6a and get final product, have no particular limits, but in order to grow the second good nitride semiconductor film 6b of crystallinity, grow band-gap energy than the also big binary mixed crystal of the first nitride semiconductor film 6a or the nitride-based semiconductor of ternary mixed crystal, if also use GaN therein, just can grow the good stratified film of whole crystallinity.Therefore, most preferred combination is to adopt the x value 0.5 or following In _xGa _1-xN is as the first nitride semiconductor film 6a, the employing GaN combination as the second nitride semiconductor film 6b.

As embodiment preferred, be to make the two thickness of first and second nitride semiconductor films be Or below, be preferably Or below, most preferably be

Or below.Like this, by first and second nitride semiconductor films thickness separately is made as

Or below, thereby the one of any of first and second nitride semiconductor films all is in elasticity critical film thickness or following, compares with the situation of growing with thicker film, can grow the good nitride-based semiconductor of crystallinity.In addition, if by these two kinds of films all are made as

Or below, thereby make stratified film become superlattice structure, the active layer of on the stratified film of the good superlattice structure of this crystallinity, growing, then stratified film will play the such effect of resilient coating, can grow the good active layer of crystallinity.

In addition, in the present embodiment 1, the thickness of at least one side in first or second nitride semiconductor film can be made as, between the first adjoining nitride semiconductor film or different between the second adjoining nitride semiconductor film.For example, first nitride semiconductor film is being made as InGaN, when second nitride semiconductor film is made as GaN, by along with to active layer near making the thickness thickening or the attenuation gradually gradually of the InGaN layer between GaN layer and GaN layer, can make variations in refractive index in stratified film inside, therefore can form the layer that refractive index gradually changes.That is, obtain and form the same effect of nitride semiconductor layer of forming gradual change substantially.Therefore, in the such element that fiber waveguide must be arranged of for example laser diode, can form waveguide, regulate the pattern of laser with this stratified film.

In addition, also the composition of the III family element of at least one side in first or second nitride semiconductor film can be made as, between the first adjoining nitride semiconductor film or different between the second adjoining nitride semiconductor film.For example, first nitride semiconductor film is being made as InGaN, when second nitride semiconductor film is made as GaN, by increasing gradually or reduce gradually along with forming near the In that makes the InGaN layer between GaN layer and GaN layer to active layer, thereby it is the same with the situation that thickness is changed successively, can make variations in refractive index in stratified film inside, thereby form the nitride semiconductor layer of forming gradual change substantially.In addition, along with the composition of In reduces gradually, refractive index has the tendency that reduces gradually.

In addition, in embodiment 1, first and second nitride semiconductor films can the both be non-doping, also can both's Doped n-type impurity, in addition also can be among either party impurity.Undoping in order to improve crystallinity, most preferably to be, secondly is modulation doping, secondly is that the both mixes again.In addition, under the situation of both's Doped n-type impurity, the concentration of the n type impurity of first nitride semiconductor film also can be different with the concentration of the n type impurity of second nitride semiconductor film.

And then in the present embodiment 1, as shown in Figure 1, in clipping active layer 7 and territory, superposed p lateral areas, have p side stratified film 8, described p side stratified film 8 by the 3rd nitride semiconductor film 8a that contains Al with have that the different tetrazotization thing semiconductor film 8b that form with the 3rd nitride semiconductor film 8a are laminated.In p side stratified film 8, identical with n side stratified film 6, the 3rd nitride semiconductor film 8a and tetrazotization thing semiconductor film 8b preferably form at least respectively one deck or more than, add up to 3 layers or more than, and then be preferably respectively stacked at least two-layer or more than, add up to stacked four layers or more than.Further, when also stratified film being set in territory, p lateral areas, if the stratified film of Film Thickness Ratio n side is thin, then the Vf of element, threshold value just have the tendency of easy reduction.As shown in Figure 1, when p side stratified film 8 and active layer 7 join and when forming, the p side stratified film that joins with last one deck (trap layer or barrier layer) of active layer both can be the 3rd nitride semiconductor film 8a, also can be tetrazotization thing semiconductor film 8b.In addition, in Fig. 1, p side stratified film 8 joins with active layer 7 and forms, but also can have the layer that is formed by other nitride-based semiconductor between this stratified film 8 and active layer 7.

In addition, in the present embodiment 1, also can be with the 3rd, the side in the tetrazotization thing semiconductor film or two sides' thickness be made as, between the 3rd adjoining nitride semiconductor film or different between the adjoining tetrazotization thing semiconductor film.For example, the 3rd nitride semiconductor film is being made as AlGaN, when tetrazotization thing semiconductor film is made as GaN, by along with thickening gradually near the thickness that makes the AlGaN layer between GaN layer and GaN layer to active layer or attenuate gradually, thereby can make variations in refractive index in stratified film inside, so, can form the layer that refractive index gradually changes substantially.That is, obtain and form the identical effect of nitride semiconductor layer of composition gradual change substantially.Therefore, in the such element that fiber waveguide, light confining bed must be arranged of for example laser diode, this multilayer film can be also used as waveguide and confining bed, regulate the pattern of laser.

In addition, also the composition of side in third and fourth nitride semiconductor film or two sides' III family element can be made as, between the 3rd adjoining nitride semiconductor film or different between the adjoining tetrazotization thing semiconductor film.For example, first nitride semiconductor film is being made as AlGaN, when second nitride semiconductor film is made as GaN, increase gradually or reduce gradually by composition along with the Al in the close AlGaN layer that makes between GaN layer and GaN layer of active layer, the same with above-mentioned mode, can refractive index be changed in stratified film inside, thereby form the nitride semiconductor layer of forming gradual change substantially.In addition, along with the composition of Al increases gradually, refractive index can reduce gradually.Therefore, can dispose the layer that these form gradual change in p layer side according to different purposes.

The 3rd nitride semiconductor film 8a is the nitride-based semiconductor that contains Al, is preferably the Al of ternary mixed crystal _aGa _1-aN (0＜x＜1) most preferably is a value and is 0.5 or following Al _aGa _1-aN.If the value of a surpasses 0.5, just have crystallinity and degenerate, be easy to generate the tendency of crackle.On the other hand, tetrazotization thing semiconductor film 8b is so long as form the nitride semiconductor film different with the 3rd nitride semiconductor film 8a and get final product, have no particular limits, but in order to grow the good tetrazotization thing semiconductor film 8b of crystallinity, normally grow band-gap energy than the also little binary mixed crystal of the 3rd nitride-based semiconductor or the nitride-based semiconductor of ternary mixed crystal, if wherein use GaN, just can grow the good stratified film of whole crystallinity.Therefore, as most preferred combination, be that the 3rd nitride semiconductor film 8a is that a value is 0.5 or following Al _aGa _1-aN, tetrazotization thing semiconductor film 8b are the combination of GaN.

Further, the thickness with the 3rd nitride semiconductor film 8a is made as

Or below, be preferably

Or below, most preferably be

Or below.Equally, the thickness of tetrazotization thing semiconductor film 8b also is made as

Or below, be preferably

Or below, most preferably be

Or below.Like this, be made as by thickness the first or second single nitride semiconductor film

Or below, thereby the thickness of this nitride-based semiconductor just is positioned at elasticity critical film thickness or following, compare with the situation of growing with thicker film, can grow the good nitride-based semiconductor of crystallinity, in addition, because the crystallinity of nitride semiconductor layer makes moderate progress, therefore under the situation of adding p type impurity, big and the little p layer of resistivity of carrier concentration can be obtained, the Vf, threshold value of element etc. can be reduced.

The 3rd nitride semiconductor film 8a and tetrazotization thing semiconductor film 8b can the both be non-doping, also can both's doped p type impurity, in addition, also can be in any one party doped p type impurity.For obtaining the high p layer of carrier concentration, most preferably carry out modulation doping.In addition, as mentioned above, under the situation of non-doping, thickness will be preferably at 0.1 μ m or following

Or below, more preferably exist Or below.This is that the resistance value of non-doped layer just has the tendency of increase because if surpass 0.1 μ m.When in both all during doped p type impurity, the concentration of the p type impurity of the 3rd nitride semiconductor film 8a also can be different with the concentration of the p type impurity of tetrazotization thing semiconductor film 8b.

In the nitride semiconductor device of above embodiment 1, in territory, p lateral areas 40, form p side stratified film 8, but the present invention is not limited only to this, also can form the p side coating layer 18 of individual layer as shown in Figure 2, replace p side stratified film 8.In addition, in the nitride semiconductor device of Fig. 2, constitute territory, p lateral areas 41 by p side coating layer 18 and p side contact layer 9.

Variation

Be to be the explanation that example is carried out in above embodiment 1, but the present invention is not limited only to this, even be applied in the laser diode, also can accesses the effect identical, and then can also carry out the distortion as following with embodiment 1 with the LED element.

Promptly, in the LD element, for example, by first nitride semiconductor film that will constitute by InGaN and the second nitride semiconductor film interaction cascading that constitutes by GaN, constitute n side stratified film, and so that the thickness of first nitride semiconductor film constitute towards the mode that the active layer direction thickens successively.By constituting n side stratified film by this way, in n side stratified film, the closer to active layer, the ratio of the InGaN that refractive index is big is big more, and n side stratified film is become along with also big more near its refractive index of active layer, has the layer of gradually changed refractive index.

In addition, in the LD element, by the 3rd nitride semiconductor film that will constitute by AlGaN and the tetrazotization thing semiconductor film interaction cascading that constitutes by GaN, constitute p side stratified film, and so that the thickness of the 3rd nitride semiconductor film constitute towards the mode of active layer direction attenuate successively.By constituting p side stratified film by this way, in p side stratified film, the closer to active layer, the ratio of the AlGaN that refractive index is little is more little, and p side stratified film is become along with also big more near its refractive index of active layer, has the layer of gradually changed refractive index.

The same with embodiment 1, because the LD element that constitutes can improve the crystallinity of each nitride semiconductor layer as described above, so can reduce threshold voltage, and can improve power output.

In addition, in the LD element, since clip the n side stratified film of active layer and p side stratified film either party can make the layer that has along with increase such gradually changed refractive index near its refractive index of active layer, so can form good fiber waveguide, can be easily and the pattern of regulating laser effectively.

Though in the LD element of last example, be by making the Thickness Variation of the first or the 3rd nitride semiconductor film, and make n side and p side stratified film become the layer of gradually changed refractive index, but the present invention is not limited only to this, also can by make second and the thickness of tetrazotization thing semiconductor film change successively, form the layer of gradually changed refractive index.

In addition, in the present invention, also can be made as, the composition of the identical III family element between the first or second adjoining nitride semiconductor film is gradually changed, and make them have gradually changed refractive index by composition with the III family element of at least one side in first or second nitride semiconductor film.For example, first nitride semiconductor film is being made as InGaN, when second nitride semiconductor film is made as GaN, by along with the ratio of the In of first nitride semiconductor film is increased gradually, just can be along with near active layer, refractive index is increased, can form the nitride semiconductor layer of same gradually changed refractive index.In addition, in InGaN, along with increasing of the composition of In, refractive index also increases.

In addition, in p side stratified film, can by make the 3rd or tetrazotization thing semiconductor film at least one side's the composition of III family element become, different between the 3rd adjoining or tetrazotization thing semiconductor film, thus form the layer of gradually changed refractive index.For example, the 3rd nitride semiconductor film is being made AlGaN, when tetrazotization thing semiconductor film is made GaN, by reducing along with the Al that makes the AlGaN layer between GaN layer and the GaN layer near active layer forms gradually, just can refractive index be gradually changed, form the nitride semiconductor layer of forming gradual change substantially in p side stratified film inside.In addition, along with the increase of the composition of Al, refractive index can diminish.Therefore, can these layers of forming gradual change be configured in p layer one side according to purpose.

Embodiment 2

Below, with reference to Fig. 4, the nitride semiconductor device of embodiment of the present invention 2 is described.

The nitride semiconductor device of embodiment of the present invention 2 is a kind of light-emitting components that have double-heterostructure on substrate 1, and described double-heterostructure has the active layer 7 that picks up the multi-quantum pit structure that comes by territory, n lateral areas 130 that is made of nitride multilayer thing semiconductor layer respectively and territory, p lateral areas 140.

In detail, in the nitride semiconductor device of embodiment 2, as shown in Figure 4, territory, n lateral areas 30 is made up of following each layer: resilient coating 102, the GaN layer 103 of non-doping, the n side contact layer 4 that contains n type impurity contains n side first stratified film 105 of n type impurity, and n side second stratified film 6 that is made of the first nitride semiconductor film 106a and the second nitride semiconductor film 106b; 30 in territory, p lateral areas is made of the p side GaN contact layer 9 by the p side coating layer 108 that multilayer film or monofilm constituted and the Mg that mixed.In addition, in the nitride semiconductor device of embodiment 2, on n side contact layer 4, form n electrode 12 respectively, on p side GaN contact layer 9, formed p electrode 11.

In addition, in Fig. 4, shown the example that has used the multilayer film that the 3rd nitride semiconductor film 108a and tetrazotization thing semiconductor film 108b be laminated as p side coating layer 108.

In the present invention,, can use, also have other such as spinelle (MgAl with sapphire C face, R face or A face sapphire as interarea as substrate 1 ₂O ₄) such insulated substrate, and SiC (containing 6H, 4H, 3C), Si, ZnO, semiconductor substrates such as GaAs, GaN.

In the present invention, as the material of resilient coating 102, be by Ga _dAl _1-dThe nitride-based semiconductor that N (condition is that d is in the scope of 0＜d≤1) forms, the ratio that is preferably Al is more little, and crystalline improvement is remarkable more, is more preferably the resilient coating 102 into being formed by GaN.

The thickness of resilient coating 102 is adjusted into the scope of 0.002～0.5 μ m, is preferably the scope of 0.005～0.2 μ m, more preferably the scope of 0.01～0.02 μ m.If the thickness of resilient coating 102 is in above-mentioned scope, the crystal habit of nitride-based semiconductor is just improved, and the crystallinity of the nitride-based semiconductor of growth also can improve on resilient coating 102.

The growth temperature of resilient coating 102 is adjusted into 200～900 ℃ scope, is preferably 400～800 ℃ scope.When growth temperature is in the said temperature scope, can obtain good polycrystalline, be crystal seed with this polycrystalline, just can improve the crystallinity of the nitride-based semiconductor of growth on resilient coating 102, thereby preferred.

In addition, the resilient coating 102 of growing under such low temperature also can dispense according to the kind of substrate, growing method etc.

Next, in the present embodiment 2, the GaN layer 103 of non-doping is the time not add n type impurity and the layer that grows in growth.If the GaN layer 103 of this non-doping of growth just can improve the crystallinity of the GdN layer 103 of non-doping on resilient coating 102, the crystallinity of n side contact layer 4 grades of growing on the GaN layer 103 that can also improve in non-doping.The thickness of the GaN layer 103 of non-doping be 0.01 μ m or more than, be preferably 0.5 μ m or more than, be more preferably 1 μ m or more than.When thickness is in this scope, n side contact layer 4 later each layer crystallinity are grown well, thereby preferred.In addition, the upper limit of the thickness of the GaN layer 103 of non-doping is had no particular limits, wait suitably and adjust but should consider to make efficient.

Next, in the present embodiment 2, contain in the n side contact layer 4 of n type impurity and contain 3 * 10 ¹⁸/ cm ³Or more than, be preferably 5 * 10 ¹⁸/ cm ³Or the n type impurity of above concentration.When the n type impurity that mixes a large amount of like this, and should layer when the n side contact layer, just can reduce Vf and threshold value.If the concentration of impurity exceeds above-mentioned scope, the tendency that is difficult to reduce Vf will be arranged.In addition, if the contact layer 4 of n side is formed on the GaN layer 103 of the non-doping that n type impurity concentration is low, crystallinity is good, also it doesn't matter even the n type impurity of high concentration is then arranged very, and still can form good crystallinity.The present invention is for the not special restriction of the upper limit of the n type impurity concentration of n side contact layer 4, and the crystallinity in order to ensure being used to keep the excellent contact layer function is preferably 5 * 10 ²¹/ cm ³Or below.

The composition of n side contact layer 4 can be with In _eAl _fGa _1-e-fN (0≤e, 0≤f, e+f≤1) constitutes, though its composition does not need to be particularly limited, is 0.2 or following Al if make GaN or f value _fGa _1-fN just can obtain the few nitride semiconductor layer of crystal defect at an easy rate, thereby preferred.Though the thickness of n side contact layer 4 needn't be particularly limited,,, most preferably be 1～5 μ m so will between 0.1～20 μ m, be preferably 0.5～10 μ m because be the layer that forms the n electrode.If thickness in above-mentioned scope, just can reduce resistance value, reduce the forward voltage of light-emitting component, thereby preferred.

In addition, n side first stratified film 105 described later is formed thicker film, and when being used as contact layer and using, can dispense n side contact layer 4.

Next, in the present embodiment 2, n side first stratified film 105 is different but have that multilayer film that identical at least two kinds of nitride semiconductor layers forming are laminated constitutes by the concentration difference of n type doping impurity and band-gap energy doping content also different or n type impurity.The thickness of n side first stratified film 105 is 2 μ m or following, is preferably 1.5 μ m or following, more preferably 0.9 μ m or following.If thickness in above-mentioned scope, just can improve luminous power output, thus preferred.In addition, its lower limit is not particularly limited, for example, can 0.05 μ m or more than.

The impurity concentration difference of the nitride semiconductor layer that constitutes above-mentioned stratified film between mutually is called as modulation doping, at this moment, and the layer that is preferably the side state of impurity that undopes, promptly non-doping.

Below, be that situation by the folded layer by layer multilayer film that forms of the mutually different at least two kinds of nitride semiconductor films of band-gap energy describes at first with regard to n side first stratified film 105.

The thickness that constitutes the little nitride semiconductor layer 105b of nitride semiconductor layer 105a stratified film, that band-gap energy is big of n side first stratified film 105 and band-gap energy is adjusted into

Or below, and then be preferably Or below, most preferably be

Scope.When than

When also wanting thick, the thickness of the nitride semiconductor layer that nitride semiconductor layer that band-gap energy is big and band-gap energy are little just reached strain the limit or more than, just have and be easy to produce tendencies such as small crackle or crystal defect in the rete.To the not special restriction of lower limit of the thickness of the little nitride semiconductor layer of the big nitride semiconductor layer of band-gap energy and band-gap energy,, but as mentioned above, most preferably be as long as thickness is at an atomic layer or above just passable

Or more than.

As mentioned above, if n side first stratified film 105 is very thin multi-layer film structures of thickness separately, just the thickness of each layer that constitutes the nitride semiconductor layer of this stratified film elasticity critical film thickness or following can be made, the considerably less nitride-based semiconductor of crystal defect can be grown.Further, can stop to a certain extent in this stratified film, produce from the logical until crystal defect of the contact layer 4 of the GaN layer 103 of non-doping or n side of substrate, can improve the crystallinity of n side second stratified film 106 of on stratified film, growing.Further, also has the effect that is similar to HEMT.

The nitride semiconductor layer 105a that band-gap energy is big is preferably the nitride-based semiconductor that contains Al at least, more preferably grows Al _gGa _1-gN (0＜g≤1).On the other hand, the nitride-based semiconductor 105b that band-gap energy is little, so long as the band-gap energy nitride-based semiconductor 105a little nitride-based semiconductor bigger than band-gap energy get final product, be which type of nitride-based semiconductor can, but be preferably Al _hGa _1-hN (0≤h＜1, g＞h), In _jGa _1-jThe such binary mixed crystal of N (0≤j＜1), the nitride-based semiconductor of ternary mixed crystal, because its easy growth, and obtain good crystallinity easily.Wherein, be preferably the big nitride-based semiconductor 105a of band-gap energy especially for not containing the Al of In in fact _gGa _1-gN (0＜g＜1), the nitride-based semiconductor 105b that band-gap energy is little is the In that does not contain Al in fact _jGa _1-jN (0≤j＜1), wherein, in order to obtain the stratified film of excellent in crystallinity, the mixed crystal that most preferably is Al is 0.3 or following Al than (g value) _gGa _1-gThe combination of N (0＜g≤0.3) and GaN.

In addition, when with n side first stratified film 105 as light confining bed and charge carrier confining bed, when making its function, must grow the band-gap energy also big nitride-based semiconductor of band-gap energy than the trap layer of active layer with coating layer.The big nitride semiconductor layer of so-called band-gap energy, the mixed crystal that is exactly Al is than high nitride-based semiconductor.In the past, if with the mixed crystal of thick film growth Al than high nitride-based semiconductor, just be easy to occur crackle, therefore, the growth of crystallization is difficulty very.Yet, if as the present invention, n side first stratified film 105 is made stratified film, all make the mixed crystal of Al than quite high rete even then will constitute each nitride semiconductor layer (105a, 105b) of stratified film, because the thickness that grows into is at the elasticity critical film thickness or below it, so be not easy to crack.Therefore, owing to can crystallinity grow the Al mixed crystal well than high rete, thus can improve the effect that light sealing and charge carrier seal, and can reduce threshold voltage in the laser diode and the Vf (forward voltage) in the LED element.

Further, it is different to be preferably the concentration of the n type impurity between the big nitride semiconductor layer 105a of the band-gap energy of n side first stratified film 105 and the little nitride semiconductor layer 105b of band-gap energy.Here it is so-called modulation doping if therefore reduce when the concentration of the n type impurity of a side layer, is preferably the state (non-doping) of the impurity that undopes, and the opposing party then is doping to high concentration, just can reduce threshold voltage, Vf etc.This is because by the low layer of impurity concentration is present in the stratified film, the mobility of this layer increases, and in addition by also existing the high layer of impurity concentration simultaneously, just can keep very high carrier concentration and forms stratified film.That is, may be owing to exist low and mobility is high layer and impurity concentration height and the big layer of carrier concentration of impurity concentration simultaneously, and make carrier concentration greatly, rete that mobility is also big becomes coating layer, thereby reduced threshold voltage and Vf.

The situation of the n type impurity of doping volume in the big nitride semiconductor layer 105a of band-gap energy, the preferred doping as among the big nitride semiconductor layer 105a of band-gap energy is adjusted into 1 * 10 ¹⁷/ cm ³～1 * 10 ²⁰/ cm ³Scope, more preferably 1 * 10 ¹⁸/ cm ³～5 * 10 ¹⁹/ cm ³Scope.If than 1 * 10 ¹⁷/ cm ³Also will lack, then the difference with the little nitride semiconductor layer of band-gap energy will reduce, thereby has the tendency that is difficult to obtain the big layer of carrier concentration, in addition, if than 1 * 10 ²⁰/ cm ³Also want many, then have the tendency that makes that easily the leakage current of element self increases.On the other hand, as long as the concentration of the n type impurity of the nitride semiconductor layer that band-gap energy is little is lower than the big nitride semiconductor layer of band-gap energy, be preferably hang down 1/10 or more than.Most preferably be non-doping, can obtain the rete of mobility maximum like this, but because thickness is too thin, have the n type impurity of coming from the big nitride-based semiconductor one side diffusion of band-gap energy, its amount is preferably 1 * 10 ¹⁹/ cm ³Or below.As n type impurity, selection be IVB family, group vib element in the periodic tables such as Si, Ge, Se, S, O, preferably with Si, Ge, S as n type impurity.Its effect also situation with a small amount of n type impurity that mixes in the big nitride semiconductor layer of band-gap energy, a large amount of n type impurity that mix in the little nitride semiconductor layer of band-gap energy is identical.

Though the situation that impurity is preferably modulation doping in the subtend stratified film is illustrated, the impurity concentration among the little nitride semiconductor layer 105b of big nitride semiconductor layer 105a of band-gap energy and band-gap energy is equated in the above.

And then in addition, in nitride semiconductor layer 105a, the 105b of the stratified film that constitutes n side first stratified film 105, the layer of the impurity of the high concentration of having mixed, on thickness direction, be preferably impurity concentration height near the semiconductor layer core, and the impurity concentration low (being preferably non-doping) at close two ends.Specifically, for example, form at the GaN layer of using AlGaN that Si is mixed as n type impurity and non-doping under the situation of stratified film, because mixed Si among the AlGaN, as the alms giver, be with electron transport to conduction band, but electronics can be absorbed in the conduction band of GaN of low potential.In the GaN crystallization, because do not mix donor impurity, so can not be subjected to the at random of the charge carrier that causes by impurity.Therefore, electronics can be movable in the GaN crystal at an easy rate, improved the mobility of the electronics of essence.This is similar to the effect of two dimensional electron gas, and the actual migration rate of electronics transverse direction has improved, and resistivity has reduced.Further, if at the n type impurity of the central area doped with high concentration of the big AlGaN of band-gap energy, effect will further increase.That is, because the electronics that in GaN, moves, more or less all can cause ion (being the Si ion at this moment) at random of the n type impurity that is included among the AlGaN.,, just be difficult to make Si at random, so improved the mobility of the GaN layer of non-doping further if the both ends of the thickness direction of AlGaN layer are non-doping.

Next, n side first stratified film 105 is laminated by the same nitride semiconductor layer of forming, n type impurity is to describe with the situation of different doped in concentrations profiled between those nitride semiconductor layers.

At first, the nitride-based semiconductor as constituting n side first stratified film 105 is not restricted to specific composition especially, so long as identical composition gets final product, can enumerate GaN as preferable material.When constituting n side first stratified film 105 with GaN, the GaN of binary mixed crystal can grow more well than ternary mixed crystal crystallinity, and the crystallinity of the nitride-based semiconductor that is grown out after can making is also very good.

In embodiment of the present invention 2, n type first stratified film 105 can use multilayer film, described multilayer film be with by the nitride semiconductor layer 105a that GaN constituted that contains n type impurity be laminated by the nitride semiconductor layer 105b that GaN constituted with n type impurity concentration different with this nitride semiconductor layer 105a.In this case, in nitride semiconductor film 105a, 105b, preferred any one party is the film of non-doping.

Even use by n side first stratified film that two kinds of nitride semiconductor layers that the different mode modulation doping of doping n type impurity forms constitute also can be obtained and the identical effect of situation different by band-gap energy and n side first stratified film 105 that two kinds of retes constituted that modulation doping forms at least to form identical.

The concentration of n type impurity is 1 * 10 ¹⁷/ cm ³～1 * 10 ²¹/ cm ³, be preferably 10 ¹⁸/ cm ³～1 * 10 ¹⁹/ cm ³, be more preferably 3 * 10 ¹⁸/ cm ³～7 * 10 ¹⁸/ cm ³In addition, in the present invention, the total film thickness of n side first stratified film 105 though there is no particular limitation, is generally

Be preferably

In addition, the thickness of each layer of formation multilayer film is

Or below, be preferably

Or below, more preferably

Or below.In addition, the lower limit of the thickness of each layer of formation multilayer film also is not particularly limited, so long as an atomic layer or above getting final product, but be preferably Or more than.When thickness is in above-mentioned scope, just can crystallinity grows well, and can improve luminous power output.

In addition, more than said n side first stratified film 105 can double as n side contact layer use, described n side first stratified film by the band-gap energy difference or form identical and impurity concentration is different two kinds or above rete constituted.At this moment, the thickness of n side first stratified film 105 is 0.5～4 μ m, is preferably 1～3 μ m, more preferably 2～2.8 μ m.The thickness of n side first stratified film 105 of this moment can be adjusted according to the stacked number of plies of above-mentioned two or more at least nitride semiconductor layer and/or the thickness of each tunic.In addition, the thickness of each tunic of formation n side first stratified film 105 of this moment can be the stratified film of the thin layer of above-mentioned scope, in addition, as long as in the above-mentioned thickness scope of n side first stratified film 105 of thickness when double as n side contact layer as a whole, the thickness of each layer also can be adjusted according to surpassing two kinds of above-mentioned scope or above nitride-based semiconductor.

In addition, as shown in Figure 4, in the present embodiment 2, has n side second stratified film 106 in the territory, n lateral areas 130 of the bottom that is arranged in active layer 7, described n side second stratified film 106 is by the first nitride semiconductor film 106a that contains In, is laminated with having with the second nitride semiconductor film 106b of the different compositions of the first nitride semiconductor film 106a.In n side second stratified film 106, form one deck or the above first nitride semiconductor film 106a and the second nitride semiconductor film 106b at least respectively, add up to two-layer or more than, be preferably three layers or more than, most preferably be respectively form two-layer at least or more than, add up to four layers or more than.

When n side second stratified film 106 joins with active layer 7 and when forming, that one deck that joins with initial one deck (trap layer or barrier layer) of active layer 7, both can be the first nitride semiconductor film 106a, also can be the second nitride semiconductor film 106b, needn't do special qualification the stacked order of n side second stratified film 106.In addition, in Fig. 4,, between this n side second stratified film 106 and active layer 7, also can have the layer that constitutes by other n type nitride-based semiconductor though n side second stratified film 106 joins with active layer 7 and forms.

In the present embodiment 2, preferably in n side second stratified film 106, the thickness of at least one side among above-mentioned first nitride semiconductor film 106a or the above-mentioned second nitride semiconductor film 106b is made as

Or below.In addition, more preferably the thickness of the above-mentioned first nitride semiconductor film 106a and the second nitride semiconductor film 106b all is made as

Or below, and then be preferably

Or below, most preferably be

Or below.Like this, because the thickness attenuation of film, n side second stratified film 106 has just become superlattice structure, just can improve the crystallinity of n side second stratified film 106, so can improve power output.

Like this,, just luminous power output can be further improved, the voltage (Vf) of positive direction can be further reduced if said n side first stratified film 105 and said n side second stratified film 106 are combined, thus preferred.Though its reason is not also determined, can think owing to can further improve the crystalline cause of the active layer of growth on n side second stratified film 106.

First nitride semiconductor film is the nitride-based semiconductor that contains In, is preferably the In of ternary mixed crystal _kGa _1-kN (0＜k＜1), and then to be preferably the k value be 0.5 or following In _kGa _1-kN most preferably is the k value and is 0.2 or following In _kGa _1-kN.On the other hand, second nitride semiconductor film is so long as the nitride-based semiconductor different with the composition of first nitride semiconductor film is just passable, have no particular limits, but in order to grow the second good nitride-based semiconductor of crystallinity, make band-gap energy than the growing nitride semiconductor of also big binary mixed crystal of first nitride-based semiconductor or ternary mixed crystal in n side second stratified film 106, the second nitride semiconductor film 106b is preferably In _mGa _1-mN (0≤m＜1, m＜k),, most preferably be GaN in order to grow all good stratified film of all crystallinity.Therefore, most preferred combination is that to adopt the k value be 0.5 or following In _kGa _1-kN is the combination of second nitride semiconductor film as first nitride semiconductor film, employing GaN.

And then, the thickness of at least one side among above-mentioned first nitride semiconductor film 106a or the above-mentioned second nitride semiconductor film 106b, both can be different mutually between the first adjoining nitride semiconductor film 106a or between the second adjoining nitride semiconductor film 106b, also can be identical.In addition, so-called thickness is different at adjoining interlayer, for example be meant that under the situation that forms the stratified film that the first nitride semiconductor film 106a or the second nitride semiconductor film 106b is multilayer laminated the thickness of the first nitride semiconductor film 106a (the second nitride semiconductor film 106b) that clips the second nitride semiconductor film 106b (the first nitride semiconductor film 106a) is different mutually.

For example, the first nitride semiconductor film 106a is made as InGaN, when the second nitride semiconductor film 106b is made as GaN, because the thickness by making the InGaN layer between GaN layer and the GaN layer is along with thickening gradually or attenuate near active layer, can make variations in refractive index in stratified film inside, so can form the layer that refractive index gradually changes substantially.That is, can obtain and form the same effect of nitride semiconductor layer of forming gradual change substantially.Therefore, in the such element that must have fiber waveguide of for example laser diode, can form waveguide, thereby regulate the pattern of laser with stratified film.

And then in addition, the composition of the III family element of at least one side among above-mentioned first nitride semiconductor film 106a or the above-mentioned second nitride semiconductor film 106b also can be different between the composition of identical III family element between the first adjoining nitride semiconductor film 106a or between the second adjoining nitride semiconductor film 106b.This just means, under the situation that forms the stratified film that the first nitride semiconductor film 106a or the second nitride semiconductor film 106b is multilayer laminated, the ratio of components of III family element of the first nitride semiconductor film 106a (the second nitride semiconductor film 106b) that clips the second nitride semiconductor film 106b (the first nitride semiconductor film 106a) is different mutually.

For example, if make the composition of identical III family element different mutually, then the first nitride semiconductor film 106a is being made as InGaN, the second nitride semiconductor film 106b is made as under the situation of GaN, the composition of In by making the InGaN layer between GaN layer and the GaN layer is along with increasing gradually near active layer or reducing, just can be the same with above-mentioned embodiment, make to change in the stratified film inner refractive index, form the nitride semiconductor layer of forming gradual change substantially.In addition, along with the minimizing that In forms, refractive index also has along with the tendency that reduces.

Though n side second stratified film 106 also can leave and form with active layer, most preferably be and join with active layer and form.Join with active layer and have the tendency of easier raising power output when forming.

In addition, in n side second stratified film 106, the first nitride semiconductor film 106a and the second nitride semiconductor film 106b can the both be non-doping, also can be in both Doped n-type impurity all, in addition also can be in any one party impurity.In order to improve crystallinity, improve power output, most preferably be and undope, secondly be modulation doping n type impurity in any one party among the first nitride semiconductor film 106a or the second nitride semiconductor film 106b, next be all impurities of two sides.

In addition, two sides all under the situation of Doped n-type impurity, the concentration of the n type impurity of the first nitride semiconductor film 106a also can be different with the concentration of the n type impurity of the second nitride semiconductor film 106b.

In addition, as n type impurity, preferably select IV family, VI family elements such as Si, Ge, Sn, S, and then preferably use Si, Sn.

Here, so-called non-doping refers to the subjective not state of impurity expressly, for example because diffusion and sneak into impurity from adjacent nitride semiconductor layer still is called non-doping in the present invention.In addition, the concentration of the impurity of sneaking into because of diffusion distribution gradient in rete mostly.

In addition, when Doped n-type impurity in the first nitride semiconductor film 106a and/or the second nitride semiconductor film 106b, the concentration of impurity is adjusted at 5 * 10 ²¹/ cm ³Or below, be preferably 1 * 10 ²⁰/ cm ³Or below.If concentration is greater than 5 * 10 ²¹/ cm ³, the crystallinity of nitride semiconductor layer will degenerate, and just has the tendency that power output is reduced.This also is like this when modulation doping.

Further, in n side second stratified film 106, the thickness of first and second nitride semiconductor films is

Or below, be preferably Or below, more preferably

Or below.By the thickness that makes single nitride semiconductor layer be

Or below, can make the thickness of nitride-based semiconductor simple layer become the elasticity critical film thickness or below it, and compare with the thick film situation of growing, can grow the good nitride-based semiconductor of crystallinity.In addition, all exist owing to two kinds of thickness

Or below, so the structure of second stratified film 6 of n side becomes superlattice (multilayer film) structure, if grow active layer on the good multi-layer film structure of this crystallinity, then n side second stratified film 6 just plays the effect of resilient coating, the active layer of just can crystallinity growing well.

In the present embodiment 2, the active layer 7 of multi-quantum pit structure by the nitride-based semiconductor that contains In and Ga, be preferably In _aGa _1-aN (0≤a＜1) and forming, be n type or p type can, but it is luminous to obtain strong interband by non-doping (not adding impurity), and the half range value of emission wavelength narrows down, thereby preferred.Also can be in active layer 7 Doped n-type impurity and/or p type impurity.If Doped n-type impurity in active layer 7, with comparing of non-doping, the interband luminous intensity can further strengthen.If doped p type impurity in active layer 7 then can make the side shifting of peak wavelength to the peak wavelength energy low 0.5eV more luminous than interband, the half range value has broadened.If two kinds of impurity of doped p type and n type in active layer just can further increase the luminous intensity of the active layer of an above-mentioned doped p type impurity.Particularly when the active layer of p type dopant had been mixed in formation, the conduction type of active layer was preferably n type dopants such as the Si that also mixes, and makes integral body become the n type.In order to grow into the active layer of good crystallinity, most preferably be non-doping.

There is no particular limitation for the stacked order of the barrier layer of active layer 7 and trap layer, can begin stackedly from the trap layer, ends up with the trap layer at last; Also can begin stackedly from the trap layer, end up with barrier layer at last.In addition, can begin stackedly, end up with barrier layer at last from barrier layer; Also can begin stackedly from barrier layer, end up with the trap layer at last.Thickness as the trap layer is adjusted into

Or below, be preferably

Or below, and then be preferably

Or below.In the present invention, the lower limit of the thickness of trap layer has no particular limits, but be generally an atomic layer or more than, be preferably

Or more than.If the thickness of trap layer ratio

Also thick, the tendency that is difficult to improve power output will be arranged.

On the other hand, the thickness of barrier layer is adjusted into

Or below, be preferably Or below, more preferably

Or below.The present invention is not particularly limited the lower limit of the thickness of barrier layer, be generally an atomic layer or more than, be preferably

Or more than.When barrier layer is in above-mentioned scope, improve power output and just be easy to, thereby preferred.Further, the present invention is not particularly limited for the whole thickness of active layer 7, considers the wavelength etc. of the expectation of LED element etc., adjusts separately stacked number, the lamination order of barrier layer and trap layer, adjusts the total film thickness of active layer 7.

In the present embodiment 2, be p side coating layer to be made by band-gap energy big the 3rd nitride semiconductor film 108a and the band-gap energy tetrazotization thing semiconductor film 108b also littler than the 3rd nitride semiconductor film 108a be laminated, and the mutual similar and different p side multilayer film coating layer 108 of p type impurity concentration.Yet, in the present invention, also can be by the Al that contains p type impurity _bGa _1-bThe simple layer that N (0≤b≤1) constitutes.

Below, at first the situation that p side coating layer is had a p side multilayer film coating layer 108 of multi-layer film structure (superlattice structure) describes.

The 3rd nitride semiconductor film 108a of the stratified film of formation p side multilayer film coating layer 108 and the thickness of tetrazotization thing semiconductor film 108b are adjusted into

Or it is following and then be preferably

Or following, most preferably be

Thickness.The thickness of the 3rd nitride semiconductor film 108a and tetrazotization thing semiconductor film 108b both can be identical, also can be different.When the thickness of each layer of multi-layer film structure is in above-mentioned scope, then the thickness of each nitride-based semiconductor is all at elasticity critical film thickness or following, compare with the situation that growth on thick film is got up, can grow the good nitride-based semiconductor of crystallinity, in addition, because the crystallinity of nitride semiconductor layer becomes well, so under the situation of having added p type impurity, can obtain the p layer that carrier concentration is big, resistivity is little, and have and be easy to reduce the Vf of element and the tendency of threshold value.Two kinds of retes of this thickness are formed a pair of, carry out repeatedly stacked, thereby formed stratified film.In addition, the adjustment of the total film thickness of p side multilayer film coating layer 108 be by each layer of adjusting third and fourth nitride semiconductor film thickness, adjust stacked number of times and carry out.The total film thickness of p side multilayer film coating layer 108 has no particular limits, but is generally

Or below, be preferably

Or below, more preferably

Or below, when total film thickness is in this scope, can improve luminous power output, reduce forward voltage (Vf), thereby preferred.

The 3rd nitride semiconductor film 108a preferably contains the nitride-based semiconductor of Al at least, more preferably makes Al _nGa _1-nN (0＜n≤1) growth; Tetrazotization thing semiconductor film 108b preferred growth goes out Al _pGa _1-pN (0≤p＜1, n＞p), In _rGa _1-rThe such binary mixed crystal of N (0≤r≤1), the nitride-based semiconductor of ternary mixed crystal.

If p side coating layer is made the p side multilayer film coating layer 108 of superlattice structure, just can improve crystallinity, reduce resistivity, and can reduce Vf.

The 3rd nitride semiconductor film 108a of p side multilayer film coating layer 108 is different with the p type impurity concentration of tetrazotization thing semiconductor film 108b, makes the impurity concentration in the side layer big, and the impurity concentration in the opposing party's layer is little.The same with n side first stratified film 5, if increase the 3rd big nitride semiconductor film 108a of band-gap energy p type impurity concentration and reduce the little tetrazotization thing semiconductor film 108b of band-gap energy p type impurity concentration or undope, so just can reduce threshold voltage, Vf etc.In addition, also can be in contrast.That is, also can reduce the concentration of the p type impurity of the 3rd big nitride semiconductor film 108a of band-gap energy, and increase the concentration of the p type impurity of the little tetrazotization thing semiconductor film 108b of band-gap energy.

Preferred doping as the 3rd nitride semiconductor film 108a is adjusted into 1 * 10 ¹⁸/ cm ³～1 * 10 ²¹/ cm ³Scope, and then be preferably 1 * 10 ¹⁹/ cm ³～5 * 10 ²⁰/ cm ³Scope.If less than 1 * 10 ¹⁸/ cm ³, same, also just diminish with the difference of tetrazotization thing semiconductor film 108b, same, have the tendency that is difficult to obtain the big rete of carrier concentration; In addition, if greater than 1 * 10 ²¹/ cm ³, then have the tendency that crystallinity degenerates.On the other hand, as long as the concentration of the p type impurity of tetrazotization thing semiconductor film 108b is than the lacking of the 3rd nitride semiconductor film 108a, be preferably less 1/10 or more than.Most preferably be and undope, so just can obtain the highest layer of mobility, but because thickness is very thin, therefore have the p type impurity of coming from the diffusion of the 3rd nitride-based semiconductor, its amount is preferably 1 * 10 ²⁰/ cm ³Or below.In addition, the situation for a spot of p type impurity that mixes in the 3rd big nitride semiconductor film 108a of band-gap energy, a large amount of p type impurity that mixes in the little tetrazotization thing semiconductor film 108b of band-gap energy is also identical.

As p type impurity, can select IIA family, IIB family element in the periodic tables such as Mg, Zn, Ca, Be, preferably with Mg, Ca etc. as p type impurity.

And then in addition, in the nitride semiconductor layer that constitutes multilayer film, the rete of high concentration ground impurity, impurity concentration near the semiconductor layer core is raise, and make impurity concentration reduce (being preferably non-doping) near both sides, can reduce resistivity like this, thus preferred.

Next, when p side coating layer be by the Al that contains p type impurity _bGa _1-bWhen the monofilm that N (0≤b≤1) forms formed, the thickness of this p side monofilm coating layer was

Or below, be preferably Or below, more preferably When thickness is in above-mentioned scope, then can improve luminous power output, reduce Vf, thereby preferred.The composition of p side monofilm coating layer is Al _bGa _1-bN (0≤b≤1).

In addition, the coating layer of individual layer rete is compared with the p side coating layer of above-mentioned multiple film layer structure, though crystallinity is weaker slightly, by with the combination of said n side first stratified film 105, can crystallinity grow well, and can reduce threshold value and Vf.And then, though be monofilm, can be by reducing the reduction of element function in this wise altogether with other film layer group, and, owing to be the individual layer rete, can simplified manufacturing technique, preferred in volume production.

The concentration of the p type impurity of p side individual layer coating layer is 1 * 10 ¹⁸/ cm ³～1 * 10 ²¹/ cm ³, be preferably 5 * 10 ¹⁸/ cm ³～5 * 10 ²⁰/ cm ³, be more preferably 5 * 10 ¹⁹/ cm ³～1 * 10 ²⁰/ cm ³If the concentration of impurity in above-mentioned scope, can obtain good p type rete, thus preferred.

Next, in the present embodiment, when the p side GaN contact layer 9 of doped with Mg is made individual layer, its composition is made the nitride-based semiconductor of the binary mixed crystal that does not contain In, Al.Under the situation of individual layer, if contain In, Al, then can not obtain the good Ohmic contact with p electrode 11, luminous efficiency will be low.The thickness of p side contact layer 9 is 0.001～0.5 μ m, is preferably 0.01～0.3 μ m, is more preferably 0.05～0.2 μ m.If thickness less than 0.001 μ m, just is easy to and p type GaAlN coating layer generation electric short circuit, be difficult to play the effect of contact layer.In addition, if GaN contact layer for the different binary mixed crystal of stacked composition on the GaAlN of ternary mixed crystal coating layer, and on the contrary its thickness is made greater than 0.5 μ m, in p side GaN contact layer 9, produce the lattice defect that forms owing to the mismatch between the crystallization with regard to being easy to, have the tendency that crystallinity descends.In addition, the thickness of contact layer is thin more, just can reduce Vf more, can improve luminous efficiency more.In addition,, just be easy to obtain p type characteristic, also be easy to obtain ohmic contact in addition if the p type impurity of this p type GaN contact layer 9 is Mg.The concentration of Mg is 1 * 10 ¹⁸/ cm ³～1 * 10 ²¹/ cm ³, be preferably 5 * 10 ¹⁹/ cm ³～3 * 10 ²⁰/ cm ³, most preferably be 1 * 10 ²⁰/ cm ³About.When the concentration of Mg is in this scope, then be easy to obtain good p type film, and Vf is reduced, thereby preferred.

In addition, n electrode 12 and p electrode 11 are respectively formed on the n side contact layer 4 and the p side GaN contact layer 9 of doped with Mg on.Material as n electrode 12 and p electrode 11 has no particular limits, and for example can use W/Al as n electrode 12, can use Ni/Au etc. as p electrode 11.

Embodiment 3

Below, with reference to Fig. 5, embodiment of the present invention 3 are described.

As shown in Figure 5, the nitride semiconductor luminescent element of embodiment of the present invention 3 is to constitute like this: on the substrate 1 that for example is made of sapphire, form a n side nitride semiconductor layer 203 successively across resilient coating 202, the 2nd n side nitride semiconductor layer 204, the 3rd n side nitride semiconductor layer 205, active layer 7, p side coating layer 108 and p side contact layer 208.In addition, in the present embodiment 3, on p side contact layer 208 roughly comprehensively on, form the p electrode 10 of light transmission, on the part of p electrode, be formed with the p pad electrode 11 that bonding is used.In addition, on a side of light-emitting component, expose the surface of the 2nd n side nitride semiconductor layer 204, on this exposed portions serve, be formed with n electrode 12.

Here, as shown in Figure 5, in the nitride semiconductor luminescent element of embodiment 3, constitute territory, n lateral areas 230 by resilient coating 202, a n side nitride semiconductor layer 203, the 2nd n side nitride semiconductor layer 204 and the 3rd n side nitride semiconductor layer 205, constitute territory, n lateral areas 240 by p side coating layer 108 and p side contact layer 208.

Here, particularly in the present embodiment 3, it is characterized in that, p side contact layer 208 has the first nitride semiconductor film 208a and the alternately laminated superlattice structure that forms of the second nitride semiconductor film 208b that has nothing in common with each other by forming, in above-mentioned two kinds of nitride semiconductor layers, at least the first nitride semiconductor film 208a contains In.Like this, constitute in above-mentioned two kinds of nitride semiconductor layers of p side contact layer 208, at least one side's the first nitride semiconductor film 208a contains In, and, the alternately laminated formation superlattice structure of the first and second nitride semiconductor film 208a, 208b can form the p side contact layer 208 that defective is few, crystallinity is good thus.Therefore, compare with the example in the past that individual layer InGaN by non-superlattice structure constitutes, it is low and can carry out the p side contact layer 208 of good Ohmic contact with p electrode 10 to form itself resistance value.

If further describe, in the present embodiment 3, p side contact layer 208 can constitute by for example first nitride semiconductor film 208a shown in the following table 1 and the second nitride semiconductor film 208b are combined again.

Table 1

	The first nitride semiconductor film 208a	The second nitride semiconductor film 208b
	The first nitride semiconductor film 208a	The second nitride semiconductor film 208b	1	In _xGa _1-xN	GaN
2	In _xGa _1-xN	In _yGa _1-yN(x＞y)	1	In _xGa _1-xN	GaN
2	In _xGa _1-xN	In _yGa _1-yN(x＞y)	3	In _xGa _1-xN	Al _yGa _1-yN(0＜z＜1)

Here, in the present embodiment 3, in order to form the first few nitride semiconductor film 8a of crystal defect, the In in the table 1 _xGa _1-xN is preferably set to x＜0.5, x＜0.4 more preferably, and then be preferably set to x＜0.3.

In addition, in the present invention, because the thickness of p type contact layer is thick more, then the resistance value of thickness direction is high more, so thickness is preferably set to 0.1 μ m or following, more preferably

Or below, and then be preferably

Or below.In addition, the thickness of first and second nitride semiconductor films of formation p type contact layer is preferably set to respectively

Or below, more preferably Or below, and then be preferably

Or below.In addition, most preferably be and be set in

Scope in.

Why the thickness that constitutes the first and second nitride semiconductor film 208a, the 208b of p side contact layer 208 will be set in

Below, be because if the thickness of the first and second nitride semiconductor film 208a, 208b greater than

, each nitride semiconductor layer just becomes the above thickness of strain limit, is easy to produce small crackle or crystal defect in rete, can not bring into play the effect as superlattice structure effectively.In addition, in the present invention, the first and second nitride semiconductor film 208a, 208b need only and are at least one atomic layer or above, are preferably as described above to be set at

Or more than.

In addition, in the present invention, need only p type impurity such as at least any one party of the first nitride semiconductor film 208a and the second nitride semiconductor film 208b, adding Mg, make p side contact layer 208 show that on the whole p type conductivity gets final product.In addition, when in the first nitride semiconductor film 208a and the second nitride semiconductor film 208b, all during doped p type impurity, preferably making the concentration height (hereinafter referred to as modulation doping) of the p type impurity concentration of side's nitride semiconductor layer than the opposing party's nitride semiconductor layer impurity.

Like this, in the first nitride semiconductor film 208a and the second nitride semiconductor film 208b, by a side impurity concentration being set than the opposing party's height, can in the high side's of impurity concentration nitride semiconductor layer, produce more charge carrier, can make the nitride semiconductor layer height of mobility ratio one side in the low the opposing party's of impurity concentration the nitride semiconductor layer.Thus, owing to can increase super lattice structure layers carrier concentration and the mobility on the whole that is laminated by the first and second nitride semiconductor film 208a, 208b simultaneously, therefore can reduce the resistance value of p side contact layer 208.Therefore, by further carry out modulation doping as described above in p side contact layer 208, the nitride semiconductor device of the present embodiment 3 can reduce the voltage of the positive direction under the predetermined electric current value.

In addition, when carrying out modulation doping like that as mentioned above, preferably in a side nitride semiconductor layer, mix 1 * 10 ¹⁹/ cm ³～5 * 10 ²¹/ cm ³The p type impurity of scope, and in the opposing party's nitride semiconductor layer, mix 5 * 10 ¹⁸/ cm ³～5 * 10 ¹⁹/ cm ³Scope, and than a spot of p type of an above-mentioned side's nitride semiconductor layer impurity.If in nitride semiconductor layer, add more than 5 * 10 ²¹/ cm ³The p type impurity of amount, crystallinity is degenerated, resistance value is raise, and is difficult to obtain good Ohmic contact; If be less than 5 * 10 ¹⁸/ cm ³, then can not obtain sufficient carrier concentration, power output will reduce.

In addition, in the present invention, in p side contact layer 208, any skim among the first nitride semiconductor film 208a or the second nitride semiconductor film 208b can be made as the superiors, also can join with any one deck and p side coating layer 108.Yet, in the present invention, preferably constitute will contain In the first nitride semiconductor film 208a as the superiors, on this first nitride semiconductor film 8a, form the p electrode.So, just can reduce ohmic contact resistance between p side contact layer 208 and the p electrode.

Promptly, the first nitride semiconductor film 208a is because contain In or contain a large amount of In, so compare with the second nitride semiconductor film 208b band gap is reduced, the energy level that can make the metal conduction band lower end that constitutes the p electrode reduces with difference between the energy level of the valence band upper end of the first nitride semiconductor film 208a, so can reduce ohmic contact resistance.

In addition, in the nitride semiconductor luminescent element of the present embodiment 3, above-mentioned p type coating layer preferably has by Al _xGa _1-xThe layer that N (0＜x≤1) constitutes and by In _yGa _1-yThe alternately laminated superlattice structure that forms of rete that N (0≤y＜1) constitutes.The thickness that constitutes each layer of this p type coating layer is preferably set to strain boundary or following, promptly

Or below, more preferably

Or below, and then be preferably

Or below, most preferably be set in

Scope in.By p type coating layer is made superlattice structure, just can reduce the resistance value of p type coating layer like this.In addition, the whole thickness of p side coating layer 108 is preferably set to And then be preferably

By setting such thickness for, just can carry out work, and the resistance value of p side coating layer integral body is also lower as good charge carrier confining bed.

Embodiment 4

As shown in Figure 6A, nitride semiconductor device of embodiment of the present invention 4 and embodiment 3 differences are, in p side contact layer 208, further form between the first nitride semiconductor film 208a and the second nitride semiconductor film 208b and form graded bedding 208c, other are all identical with embodiment 3.Here, the so-called graded bedding 208c that forms, be meant with from the composition of the first nitride semiconductor film 208a to the mode that the composition of the second nitride semiconductor film 208b slowly changes, make composition continually varying layer on thickness direction.For example, be In at the first nitride semiconductor film 208a _xGa _1-xN, the second nitride semiconductor film 208b is under the situation of GaN, forming graded bedding 208c is such rete: shown in Fig. 6 B, from with the first nitride semiconductor film 208a join towards the face that joins with the second nitride semiconductor film 208b, along thickness direction, the proportion of composing of In (x) reduces gradually.In addition, in the present embodiment 2, be reduce gradually just passable as long as form the proportion of composing of graded bedding 208c, not necessarily to leave no choice but as shown in Fig. 6 B, composition linearly changes at thickness direction.

The nitride semiconductor device of the embodiment 2 of Gou Chenging as described above, because being great-jump-forward, the composition on the watershed area of the first nitride semiconductor film 208a and the second nitride semiconductor film 208b do not change, therefore, when coating growth, in the watershed area of the first nitride semiconductor film 208a and the second nitride semiconductor film 208b, can prevent the segregation of element-specific.Like this, can prevent that the result of the segregation of element-specific from being, can grow the crystal defect first nitride semiconductor film 208a and the second nitride semiconductor film 208b still less.

At the above-mentioned first nitride semiconductor film 208a is In _xGa _1-xN, the second nitride semiconductor film 208b is in the example of GaN, can prevent the segregation of the In between the first nitride semiconductor film 208a and the second nitride semiconductor film 208b, can improve crystallinity.

Embodiment 5

Below, using its constructed profile is that Fig. 8 comes the nitride semiconductor device of embodiment of the present invention 5 is described.

As shown in Figure 8, the nitride semiconductor device of embodiment 5 has following structure, promptly, each rete below having stacked gradually on the substrate 1: resilient coating 102, the GaN layer 103 of non-doping, the n side contact layer 4 that contains n type impurity, the 305a of lower floor by non-doping, the intermediate layer 305b of n type impurity and these the three layers of n side of being formed first stratified films 305 of upper strata 305c of non-doping have mixed, n side second stratified film 306 that constitutes by the first nitride semiconductor film 306a and the second nitride semiconductor film 306b, the active layer 7 of multi-quantum pit structure, p side multilayer film coating layer 8 or the p side monofilm coating layer 8 formed by third and fourth nitride semiconductor film, and the p side GaN contact layer 9 of doped with Mg.And then, on n side contact layer 4, form n electrode 12 respectively, on p side GaN contact layer 9, form p electrode 11.

Here, in the nitride semiconductor device of embodiment, GaN layer 103, n side contact layer 4, n side first stratified film 305 and n side second stratified film 306 by resilient coating 102, non-doping constitute territory, n lateral areas 330, constitute territory, p lateral areas by p side coating layer 108 and p side GaN contact layer 9.

In the present embodiment 5, as substrate 1, can use with sapphire C face, R face or A face sapphire as interarea, can use spinelle (MgAl in addition ₂O ₄) such insulating properties substrate, and SiC (containing 6H, 4H, 3C), Si, ZnO, semiconductor substrates such as GaAs, GaN.

In the present embodiment 5,, can enumerate by Ga as resilient coating 102 _dAl _1-dThe nitride-based semiconductor that N (condition is that d is in the scope of 0＜d≤1) makes, the ratio that is preferably Al is more little, and crystalline improvement is remarkable more, more preferably the resilient coating of being made by GaN 102.

The thickness of resilient coating 102 is adjusted into 0.002～0.5 μ m, is preferably 0.005～0.2 μ m, and then is preferably in the scope of 0.01～0.02 μ m.When the thickness of resilient coating 102 was in above-mentioned scope, the crystal habit of nitride-based semiconductor was good, and the crystallinity of the nitride-based semiconductor that growth is got up on resilient coating 102 also is improved.

The growth temperature of resilient coating 102 is adjusted into 200～900 ℃, is preferably in 400～800 ℃ the scope.When growth temperature is in above-mentioned scope, will crystallize into good polycrystal, as crystal seed, just can make the crystallinity of the nitride-based semiconductor of growth on resilient coating 102 good with this polycrystal, thereby preferred.

In addition, according to the kind of substrate, the method for growth etc., also can omit the resilient coating 102 that this growth is at low temperatures got up.

Next, in the present embodiment 5, the GaN layer 103 of non-doping is illustrated in the layer that does not add n type impurity in the process of growth and grow.When the GaN layer 103 of the non-doping of growth on resilient coating 102, the crystallinity of the GaN layer 103 of non-doping is good, and the crystallinity of n side contact layer 4 grades of growth also becomes fine on the GaN of non-doping layer 103.The thickness of the GaN layer 103 of non-doping be 0.01 μ m or more than, be preferably 0.5 μ m or more than, more preferably 1 μ m or more than.When thickness is in this scope, just can crystallinity grow each later layer of n side contact layer 4 well, thereby preferably.In addition, the upper limit of the thickness of the GaN layer 103 of non-doping has no particular limits, but can suitably adjust according to factors such as production efficiencys.

Next, in the present embodiment 5, the n side contact layer 4 that contains n type impurity is with 3 * 10 ¹⁸/ cm ³Or more than, be preferably 5 * 10 ¹⁸/ cm ³Or above concentration contains n type impurity.If the n type impurity that mixes more like this, then with this rete as the n side contact layer, just can reduce Vf and threshold value.If the concentration of impurity exceeds above-mentioned scope, will be in distress so that the tendency that Vf reduces.In addition, when on n side contact layer 4 is the GaN layer 103 of very low in n type impurity concentration, that crystallinity is good non-doping, forming,, also can form good crystallinity even have the n type impurity of high concentration.The upper limit to the n type impurity concentration of n side contact layer 4 has no particular limits, but in the boundary that is in the function that can keep in touch layer, is preferably 5 * 10 ²¹/ cm ³Or below.

The composition of n side contact layer 4 can be by In _eAl _fGa _1-e-fN (0≤e, 0≤f, e+f≤1) constitutes, though its composition needn't be particularly limited, is preferably GaN, f value and is 0.2 or following Al _fGa _1-fN can obtain the few nitride semiconductor layer of crystal defect so at an easy rate.Though the thickness of n side contact layer 4 needn't limit especially, owing to be the rete that forms the n electrode, be 0.1～20 μ m therefore, be preferably 0.5～10 μ m, more preferably 1～5 μ m.When thickness is in above-mentioned scope, can reduce resistance value, and the Vf value of light-emitting component is reduced, thereby preferred.

In addition, in that following n side first stratified film 305 is formed under the situation of thick film, can omit n side contact layer 4.

Next, in the present embodiment 5, n side first stratified film 305 is made of trilamellar membrane layer at least, and from substrate-side, described trilamellar membrane layer is respectively the upper strata 305c of the 305a of lower floor of non-doping, the intermediate layer 305b of Doped n-type impurity, non-doping.

Constitute each layer of n side first stratified film 305, though separately separately may be during one deck to the influence that has nothing direct of element characteristics such as anti-electrostatic pressure, but when each layer being combined formation n side first stratified film 305, do as a wholely, the peculiar function that can significantly improve the characteristic of element, particularly luminous power output and anti-electrostatic pressure performance has just been arranged.In fact, this effect is when making each element that gathers into folds layer by layer at first and the outer effect of the anticipation that obtains, and in other words, the present invention relies on the such effect of discovery to finish.

On n side first stratified film 305, also can have the above-mentioned 305a of lower floor～upper strata 305c other layers in addition here.In addition, n side first stratified film 305 both can join with active layer, and other layer also can be arranged between it and active layer.

Nitride-based semiconductor as constituting the 305a of these lower floors～upper strata 305c can adopt by In _gAl _hGa _1-g-hN (preferably can enumerate and have the nitride-based semiconductor of forming that is made of GaN by the nitride-based semiconductor of the various compositions of expression of 0≤g＜1,0≤h＜I).In addition, the composition of each layer of first stratified film 305 both can be identical, also can be different.

Though there is no particular limitation for the thickness of n side first stratified film 305, is generally

Be preferably

More preferably

If the thickness of first stratified film 5 is preferred from the aspect of the raising of the most suitableization of Vf and anti-electrostatic pressure performance in above-mentioned scope.

Adjustment to the thickness of first stratified film 5 of thickness with above-mentioned scope is preferably the thickness of suitably regulating the 305a of lower floor, intermediate layer 305b and upper strata each layer of 305c, so that the total film thickness of first stratified film 5 is in above-mentioned scope.

In addition, in the present embodiment 5, have no particular limits though constitute the thickness of each layer of the 305a of lower floor, the intermediate layer 305b of n side first stratified film 305 and upper strata 305c, in the present invention, in order to find out the thick preferable range of each tunic, carried out following experimental study.

(1) test 1

The thickness of making the 5a of lower floor is

The thickness of intermediate layer 5b is

And the LED element that the thickness of upper strata 5c gradually changes is measured the forward voltage of each element (various thickness), luminous power output and anti-electrostatic pressure characteristic.

It the results are shown among Fig. 9 A and Fig. 9 B.

(2) test 2

The thickness of making the 5a of lower floor is

The thickness of upper strata 5c is

And the LED element that the thickness of intermediate layer 5b gradually changes is measured the forward voltage of each element (various thickness), luminous power output and anti-electrostatic pressure characteristic.

It the results are shown among Figure 10 A and Figure 10 B.

(3) test 3

The thickness of making intermediate layer 5b is

The thickness of upper strata 5c is

And the LED element that the thickness of the 5a of lower floor gradually changes is measured the forward voltage of each element (various thickness), luminous power output and anti-electrostatic pressure characteristic.

It the results are shown among Figure 11 A and Figure 11 B.

In addition, the various LED elements of made in this test, except each tunic of n side first stratified film was thick, other the manufacturing conditions all condition with the following examples 34 was identical.In addition, the characteristic shown in Fig. 9 A～Figure 11 B all is to compare with embodiment 34 and the characteristic of LED element of example in the past used.In addition, in Fig. 9 A～Figure 11 B, Po represents luminous power output, and Vf represents forward voltage.

From above test result, the thickness of the 305a of lower floor of non-doping is

Be preferably More preferably

Shown in Figure 11 A and Figure 11 B, if the thickness progressive additive of the 305a of lower floor of non-doping, anti-electrostatic pressure characteristic will rise, but

Near, Vf sharply rises; On the other hand, if the thickness attenuate, Vf also descends, and the decline of anti-electrostatic pressure characteristic increases, this be since thickness less than

The time, along with the decline of anti-electrostatic pressure characteristic, stock utilization also descends significantly.

In addition, because consider the low influence of crystallinity that improves the n side contact layer 4 that contains n type impurity, so preferred so that the thickness growth upper strata 305a of the degree that crystalline improvement is good.

The thickness of intermediate layer 305b of n type impurity of having mixed is

Be preferably More preferably

The intermediate layer 305b of this impurity that mixed makes carrier concentration fully, luminous power output is had the layer of bigger effect, if do not form this layer, just has the significantly reduced tendency of luminous power output.In addition, in Figure 10 A, shown, be reduced to until the thickness of intermediate layer 305b

During the left and right sides, luminous power output also just has decline slightly, even this is because consider that the thickness of intermediate layer 305b is

Luminous power output can not descend yet, thus the cause that the thickness of other layers is adjusted.In addition, shown in Figure 10 A, when thickness surpasses

The time, luminous power output has the tendency that descends significantly.On the other hand, shown in Figure 10 B, singly see anti-electrostatic pressure characteristic, when the thickness of intermediate layer 305b was very thick, anti-electrostatic pressure characteristic was good, and when thickness less than

The time, just have the tendency that anti-electrostatic pressure characteristic descends significantly.

The thickness of the upper strata 305c of non-doping is

Be preferably

More preferably

The upper strata 305c of this non-doping and active layer joins or the most approaching and be formed in first multilayer film with it, to the very big relation that prevents of leakage current, when the thickness of upper strata 305c less than

The time, have the tendency that leakage current increases.In addition, shown in Fig. 9 A and 9B, when the thickness of upper strata 305c surpasses

The time, Vf will rise, and anti-electrostatic pressure characteristic will descend.

As mentioned above, the thickness of the 305a of lower floor～upper strata each layer of 305c is very important for the characteristic of the element that is subjected to the thick influence of change of each tunic easily, further, in the 305a of lower floor, intermediate layer 305b and upper strata 305c combination, the various characteristics of element all roughly reaches good degree equably, particularly luminous power output and anti-electrostatic pressure characteristic become good, by being defined in the above-mentioned scope each tunic is thick, thereby can satisfy the standard of higher requirement, just can realize obtaining higher luminous power output, or further improve the reliability of commodity.

In addition, the various conditions such as shape of the variation of the composition of the active layer that the combination that first multilayer film, 305 each tunic are thick can change according to the kind along with emission wavelength or electrode, LED element are suitably adjusted, in the hope of obtaining the best effect.By the thickness of each layer of combination in above-mentioned scope suitably, can make the various performances relevant better than element in the past with the thick combination of each tunic, can obtain good luminous power output and anti-electrostatic pressure characteristic.

The composition of each layer that constitutes above-mentioned first stratified film is so long as with following formula In _gAl _hGa _1-g-hThe composition of N (0≤g＜1,0≤h＜1) expression gets final product, and the composition of each layer can be identical, also can be different, be preferably the little composition of ratio of In and Al, more preferably the rete that constitutes by GaN.

The doping of above-mentioned first stratified film 305 the not special regulation of doping of n type impurity of intermediate layer 305b of n type impurity, but the concentration that generally should contain is 3 * 10 ¹⁸/ cm ³Or more than, be preferably 5 * 10 ¹⁸/ cm ³Or more than.To the also not special regulation of the upper limit of n type impurity, but should exceed, generally be preferably 5 * 10 so that crystallinity is too worsened ²¹/ cm ³Or below.When the impurity concentration in the intermediate layer of first stratified film is in above scope, consider from the aspect that improves luminous power output and reduce Vf and preferred.

As n type impurity, can select IVB family or group vib element in the periodic tables such as Si, Ge, Se, S, O, be preferably Si, Ge, S as n type impurity.

In addition, on the interface of above-mentioned first stratified film 305, in the scope of the function that does not hinder each layer and element, each layer can use by two kinds of layers of double as.

Next, in the present embodiment 5, second stratified film 306 of n side is made of multilayer film as described below, described multilayer film by the first nitride semiconductor film 306a that contains In with have that the second nitride semiconductor film 306b that form different with this first nitride semiconductor film 306a be laminated.The thickness of at least one side among this first nitride semiconductor film 306a or the second nitride semiconductor film 306b, preferred two sides' thickness are

Or below, more preferably Or below, and then be preferably

Or below.Because by such attenuate thickness, stratified film just becomes superlattice structure, the crystallinity of stratified film has improved, so have the tendency that improves power output.

If the thickness of at least one side's film among the first nitride semiconductor film 306a or the second nitride semiconductor film 306b is

Or below, the thickness of thin layer is just below the elasticity critical film thickness, crystallization just improves, and first nitride semiconductor film 306a that gathers into folds at its upper layer or the crystallinity of the second nitride semiconductor film 306b also will be improved, the crystallinity of stratified film integral body also will be improved, so the power output of element just will improve.

In addition, if the thickness of the first nitride semiconductor film 306a and the second nitride semiconductor film 306b all be

Or below, the independent one deck of nitride-based semiconductor just is in elasticity critical film thickness or following, with situation of growing with thick film and the side among the first nitride semiconductor film 306a or the second nitride semiconductor film 306b is

Or following situation compares, and can grow the good nitride-based semiconductor of crystallinity.In addition, the film as both sides all is

Or when following, then n side second stratified film 306 just becomes superlattice structure, when growth active layer on the good multi-layer film structure of this crystallinity, it is such that n side second stratified film 306 can play resilient coating, and active layer can get up with the more crystalline growth.

In the present embodiment 5, if in territory, n lateral areas 330, said n side first stratified film 305 and said n side second stratified film 306 are made up, will improve luminous power output, reduce Vf, thereby preferred.Though its reason is undetermined, can think owing to be the good result of crystallinity change of the active layer of growth on n side second stratified film 306.

In addition, the above-mentioned first nitride semiconductor film 306a of n side second stratified film 306 or the thickness of at least one side among the second nitride semiconductor film 306b, can be between the first adjoining nitride semiconductor film 306a or different between the second nitride semiconductor film 306b, also can be identical.Be preferably the above-mentioned first nitride semiconductor film 306a of n side second stratified film 306 or the thickness of at least one side among the second nitride semiconductor film 306b, between the first adjoining nitride semiconductor film 306a or different between the second nitride semiconductor film 306b.

So-called thickness is different between adjoining layer, the meaning is that the thickness of the second nitride semiconductor film 306b (the first nitride semiconductor film 306a) is different with the thickness of the first nitride semiconductor film 306a (the second nitride semiconductor film 306b) that clips it when forming the multilayer laminated stratified film that forms of the first nitride semiconductor film 306a and the second nitride semiconductor film 306b.

For example, when the first nitride semiconductor film 306a is InGaN, when the second nitride semiconductor film 306b is GaN, the thickness of the InGaN layer between GaN layer and the GaN layer is along with the thickening gradually near active layer, perhaps attenuate gradually, thereby change in the stratified film inner refractive index, therefore can form the rete that refractive index gradually changes substantially.That is, can obtain and form the identical effect of nitride-based semiconductor of composition gradual change substantially.Therefore, in the such element that the light wave guide channel must be arranged of for example laser diode, in stratified film, form the light wave guide channel, just can regulate the pattern of laser.

In addition, the composition of the III family element of at least one side in first or second nitride semiconductor film can be between the first adjoining nitride semiconductor film 306a or different between the second adjoining nitride semiconductor film 306b, perhaps also can be identical.Preferably, the composition of the III family element of at least one side in first nitride semiconductor film or second nitride semiconductor film is between the first adjoining nitride semiconductor film or different between the second adjoining nitride semiconductor film.So-called different being meant, under the situation that forms the stratified film that first nitride semiconductor film or second nitride semiconductor film is multilayer laminated, the proportion of composing of the III family element of second nitride semiconductor film (first nitride semiconductor film), different mutually with the proportion of composing of the III family element of first nitride semiconductor film that clips it (second nitride semiconductor film).

For example, if make the composition of identical III family element different mutually, then working as first nitride semiconductor film is InGaN, when second nitride semiconductor film is GaN, the composition of In by making the InGaN layer between GaN layer and the GaN layer is along with increasing gradually near active layer, perhaps reduce, just can make variations in refractive index, can form the nitride semiconductor layer of forming gradual change substantially in stratified film inside.In addition, along with the minimizing that In forms, refractive index also has the tendency that reduces.

Said n side second stratified film 306, for example, as shown in Figure 8, clipping active layer 7 and be in the n side nitride semiconductor layer of bottom, having and to contain first nitride semiconductor film of In and to have n side second stratified film 306 that second nitride semiconductor film of the composition different with this first nitride semiconductor film is laminated.In n side second stratified film 306, first nitride semiconductor film and second nitride semiconductor film preferably form at least respectively one deck or more than, add up to two-layer or more than, be preferably 3 layers or more than, and then be preferably respectively stacked at least two-layer or more than, add up to 4 layers or more than.

N side second stratified film 306 can leave and form with active layer, joins with active layer and forms but most preferably be.When forming, the tendency of easier raising power output is arranged joining with active layer.

Join with active layer and when forming at n side second stratified film 306, the stratified film that joins with the initial rete (trap layer or barrier layer) of active layer both can be first nitride semiconductor film, also can be second nitride semiconductor film, the stacked order of n side second stratified film 306 needn't be particularly limited.In addition, though n side second stratified film 306 joins with active layer 7 and forms in Fig. 8, also can between this n side second stratified film 306 and active layer, have the rete that is constituted by other n type nitride-based semiconductors.

First nitride semiconductor film is the nitride-based semiconductor that contains In, is preferably the In of ternary mixed crystal _kGa _1-kN (0＜k＜1), and then to be preferably the k value be 0.5 or following In _kGa _1-kN most preferably is the k value and is 0.2 or following In _kGa _1-kN.On the other hand, second nitride semiconductor film is so long as the nitride-based semiconductor different with the composition of first nitride semiconductor film is just passable, not special restriction, but, make it grow into band-gap energy than first nitride semiconductor film In also big, binary mixed crystal or ternary mixed crystal in order to grow the second good nitride semiconductor film of crystallinity _mGa _1-mN (0≤m＜1, m＜k), be preferably GaN.When second nitride-based semiconductor is GaN, just can grow the good stratified film of crystallinity on the whole.As preferred combination, can enumerate first nitride-based semiconductor is In _kGa _1-k(0＜k＜l), second nitride-based semiconductor is In to N _mGa _1-mN (0≤m＜1, m＜k), is preferably the combination of GaN.As so preferred combination, be that first nitride semiconductor film is that the k value is 0.5 or following In _kGa _1-kN, and second nitride semiconductor film is the combination of GaN.

First and second nitride semiconductor films can the both be non-doping, also can be both's n type impurity that mixed, perhaps, also can be in any one party impurity (modulation doping).In order to improve crystallinity, preferred both is plain, secondly is modulation doping, is that the both mixes once more.In addition, under the situation that the both mixes, the concentration of the n type impurity in first nitride semiconductor film also can be different with the concentration of n type impurity in second nitride semiconductor film.

In addition, Doped n-type impurity in any one party in first nitride semiconductor film or second nitride semiconductor film is called modulation doping, by this modulation doping, has the tendency of easy raising power output.

In addition, as n type impurity, preferably select IV family, VI family elements such as Si, Ge, Sn, S, and then preferably adopt Si, Sn.

When Doped n-type impurity, the concentration of impurity is adjusted into 5 * 10 ²¹/ cm ³Or below, be preferably 1 * 10 ²⁰/ cm ³Or below.If more than 5 * 10 ²¹/ cm ³, the crystallinity of nitride semiconductor layer will degenerate, otherwise, just have the tendency that power output reduces.Also be like this under the situation of modulation doping.

In the present embodiment 5, the active layer 7 of multi-quantum pit structure is to be formed by the nitride-based semiconductor that contains In and Ga, is preferably by In _aGa _1-aN (0≤a＜1) forms, no matter the n type still be the p type can, if but be non-doping (not adding impurity), it is luminous just to obtain very strong interband, the half range value of emission wavelength narrows down, thereby preferably.Also can be in active layer 7 Doped n-type and/or p type impurity.When Doped n-type impurity in active layer 7, compare with non-doping, further luminous intensity between reinforcing band.When doped p type impurity in active layer 7, though can make the side shifting of peak wavelength to the peak wavelength approximately low 0.5eV energy more luminous than interband, the half range value has been widened.When doped p type in active layer and two kinds of impurity of n type, can further strengthen the luminous intensity of the active layer of above-mentioned doped p type impurity.Particularly when forming the active layer of the p type dopant that mixed, if the n type dopant of the Si that also mixed and so on, the conductivity type of active layer just is the n type on the whole, thereby preferred.In order to grow the active layer of good crystallinity, most preferably be non-doping.

The stacked order of the barrier layer of active layer 7 and trap layer needn't be particularly limited, begin to be laminated to the trap layer from the trap layer and finish, begin to be laminated to barrier layer from the trap layer and finish, begin to be laminated to barrier layer from barrier layer and finish, perhaps begin to be laminated to the trap layer and finish from barrier layer, can.Thickness as the trap layer generally is adjusted into

Or below, be preferably Or below, and then be preferably

Or below.The upper limit that the trap tunic is thick has no particular limits, but be generally an atomic layer or more than, be preferably

Or more than.When the thickness of trap layer surpasses

The time, have the tendency that power output is difficult to improve.

On the other hand, the thickness of barrier layer generally is adjusted into Or below, be preferably

Or below, more preferably

Or below.The not special restriction of the upper limit of barrier layer thickness, but be generally an atomic layer or more than, be preferably

Or more than.When barrier layer is in above-mentioned scope, just can improve power output at an easy rate, thereby preferred.In addition, the whole thickness of active layer 7 is also had no particular limits, can be after the desirable wavelength of considering LED element etc. etc., separately the stacked number of plies, the lamination order of regulating barrier layer and trap layer are adjusted the total film thickness of active layer 7.

In the present embodiment 5, p side coating layer 8 be the 3rd nitride semiconductor film that band-gap energy is big and the band-gap energy tetrazotization thing semiconductor film littler than the 3rd nitride semiconductor film gather into folds form, p type impurity concentration similar and different stratified film mutually, or by the Al that contains p type impurity _bGa _1-bThe individual layer that N (0≤b≤1) is constituted.

Below, be that the situation with p side multilayer film coating layer of multi-layer film structure (superlattice structure) describes at first to p side coating layer 8.

The thickness of third and fourth nitride semiconductor film of the stratified film of formation p side multilayer film coating layer 17 is adjusted into

Or below, and then be preferably

Or below, most preferably be

The thickness of the 3rd nitride semiconductor film and tetrazotization thing semiconductor film both can be identical, also can be different.When the thickness of each layer in the multi-layer film structure is in above-mentioned scope, each tunic of nitride-based semiconductor is thick all at elasticity critical film thickness or following, compare with the situation of growing with thick film, can grow the good nitride-based semiconductor of crystallinity, in addition, the crystallinity of nitride semiconductor layer is improved, so under the situation of having added p type impurity, can obtain the p layer that carrier concentration is big, resistivity is little, be easy to reduce the Vf and the threshold value of element.Two kinds of layers of such thickness as a pair of and repeatedly stacked, have just been formed stratified film.Next, the adjustment of p side multilayer film coating layer 8 total film thicknesses is adjusted by thickness, the stacked number of times of adjustment of adjusting third and fourth each layer of nitride semiconductor layer.The not special regulation of the total film thickness of p side multilayer film coating layer 8, but be generally

Or below, be preferably

Or below, more preferably

Or below, when total film thickness is in above-mentioned scope, luminous power output height, (Vf) is lower for forward voltage, thereby preferred.

The 3rd nitride semiconductor film preferably makes the nitride-based semiconductor that contains Al at least, is preferably Al _nGa _1-nN (0＜n≤1) grows up; Tetrazotization thing semiconductor film preferably makes Al _pGa _1-pN (0≤p＜1, n＞p), In _rGa _1-rThe such binary mixed crystal of N (0≤r≤1), the growing nitride semiconductor of ternary mixed crystal.If p side coating layer 8 is made superlattice structure, just have the tendency that crystallinity is improved, resistivity reduces, Vf reduces.

The 3rd nitride semiconductor film of p side multilayer film coating layer 8 and the p type impurity concentration of tetrazotization thing semiconductor film are different, make the impurity concentration in the side layer big, and the impurity concentration in the opposing party's layer is little.The same with the coating layer 12 of n side, the concentration of the p type impurity of the 3rd nitride semiconductor film that band-gap energy is big increases, and the concentration of the p type impurity of the tetrazotization thing semiconductor film that band-gap energy is little reduces, and is preferably to undope, and so just can reduce threshold voltage, Vf etc.In addition, also can be in contrast.That is, the concentration of the p type impurity of the 3rd big nitride semiconductor film of band-gap energy is reduced, and the concentration of the p type impurity of the little tetrazotization thing semiconductor film of band-gap energy increase.

Preferred doping as the 3rd nitride semiconductor film is adjusted into 1 * 10 ¹⁸/ cm ³～1 * 10 ²¹/ cm ³Scope in, be preferably 1 * 10 ¹⁹/ cm ³～5 * 10 ²⁰/ cm ³If less than 1 * 10 ¹⁸/ cm ³, same difference with tetrazotization thing semiconductor film will reduce, and has the tendency that is difficult to obtain the big rete of carrier concentration equally; In addition, if greater than 1 * 10 ²¹/ cm ³, just have the tendency that crystallinity worsens.On the other hand, as long as the concentration of the p type impurity of tetrazotization thing semiconductor film is less than the 3rd nitride semiconductor film, be preferably less 1/10 or more than.Most preferably be and undope, so just can obtain the highest rete of mobility, but because thickness is thin, have the p type impurity of coming from the diffusion of the 3rd nitride-based semiconductor one side, its amount is preferably 1 * 10 ²⁰/ cm ³Or below.In addition, the situation that institute's doped p type impurity is many in the tetrazotization thing semiconductor film that institute's doped p type impurity is few in the 3rd nitride semiconductor film that band-gap energy is big, band-gap energy is little is also identical.

Select IIA family, IIB family element in Mg, Zn, the periodic tables such as Ca, Be as p type impurity, preferably with Mg, Ca etc. as p type impurity.

And then in addition, in order to reduce resistivity, preferably in the nitride semiconductor layer that constitutes multilayer film, on thickness direction, make near the impurity concentration height of the layer semiconductor layer core of high-concentration dopant impurity, and near the impurity concentration both sides low (being preferably non-doping).

Next, when p side coating layer 8 is when being made of individual layer as described below, described individual layer is by the Al that contains p type impurity _bGa _1-bN (0≤b≤1) forms, and then the thickness of p side monofilm coating layer 8 is generally

Or below, be preferably

Or below, more preferably

Or below.When thickness is in above-mentioned scope, just can improve luminous power output, reduce Vf, thereby preferred.The composition of p side monofilm coating layer 8 is Al _bGa _1-bN (0≤b≤1).

In addition, though the coating layer of monofilm is compared with the p side coating layer of above-mentioned multiple film layer structure, crystallinity is weaker slightly, by with the combination of above-mentioned first stratified film 4, just can crystallinity grow well, also can reduce threshold value and Vf.And then, like this, even the individual layer rete, also can be by making the reduction quantitative change of element function few with other layers structure is combined, and owing to be the individual layer rete, so can realize the simplification of manufacturing process, preferred in volume production.

The concentration of the p type impurity of p side individual layer coating layer 8 is 1 * 10 ¹⁸/ cm ³～1 * 10 ²¹/ cm ³Scope in, be preferably 5 * 10 ¹⁸/ cm ³～5 * 10 ²⁰/ cm ³In the scope, more preferably 5 * 10 ¹⁹/ cm ³～1 * 10 ²⁰/ cm ³In the scope.If the concentration of impurity in above-mentioned scope, just can obtain good p type rete, thereby preferred.

Next, in the present embodiment 5, the composition of the p side GaN contact layer 9 of doped with Mg is the nitride-based semiconductor that does not contain the binary mixed crystal of In, Al.If contain In, Al, then can't obtain the ohmic contact with p electrode 11, luminous efficiency is low.The thickness of p side contact layer 9 is 0.001～0.5 μ m, is preferably 0.01～0.3 μ m, more preferably 0.05～0.2 μ m.If thickness less than 0.001 μ m, just is easy to and p type GaAlN coating layer generation electric short circuit, be difficult to work as contact layer.In addition, since will be on the GaAlN of ternary mixed crystal coating layer the GaN contact layer of the different binary mixed crystal of stacked composition, if on the contrary its thickness is made greater than 0.5 μ m, in p side GaN contact layer 9, produce the lattice defect that forms by the mismatch between the crystallization, the tendency that has crystallinity to descend with regard to being easy to.In addition, the thickness of contact layer is thin more, and Vf is just low more, can improve luminous efficiency more.In addition, if the p type impurity of this p type GaN contact layer 9 is Mg, just can be easy to obtain p type characteristic, and can be easy to obtain ohmic contact.The concentration of Mg is 1 * 10 ¹⁸/ cm ³～1 * 10 ²¹/ cm ³, be preferably 5 * 10 ¹⁹/ cm ³～3 * 10 ²⁰/ cm ³, more preferably 1 * 10 ²⁰/ cm ³About.When the concentration of Mg is in this scope, be easy to obtain good p type film, and Vf is reduced, thereby preferred.

In addition, n electrode 12 and p electrode 11 are respectively formed on the n side contact layer 4 and the p side GaN contact layer 9 of doped with Mg on.The not special regulation of the material of n electrode and p electrode for example can be used W/Al as the n electrode, can use Ni/Au etc. as the p electrode.

Embodiment 6

Below, the nitride semiconductor device of embodiment of the present invention 6 is described.

The nitride semiconductor device of this embodiment 6 is the nitride-based semiconductors with n type stratified film and p type stratified film, and its basic comprising is identical with embodiment 1, so suitably describe with reference to Fig. 1.

The nitride semiconductor device of embodiment 6 has stacked gradually following each layer and has formed on sapphire substrate 1: the resilient coating 2 that is made of GaN, the GaN layer 3 of non-doping, the n side contact layer 4 that constitutes by the GaN of the Si that mixed, the GaN layer 5 of non-doping, n type stratified film 6, the active layer 7 of the multi-quantum pit structure that constitutes by InGaN/GaN, p type stratified film 8, the p type contact layer 9 that constitutes by the GaN of the Mg that mixed.Constituting the composition and/or the number of plies of each nitride-based semiconductor of said n type stratified film 6 and p type stratified film 8, is different on n side and p side, and this point is different with embodiment 1.In addition, in the nitride semiconductor device of the present embodiment 6,, can use the various stratified films that illustrated in the embodiment 1～5 as n type stratified film 6 and p type stratified film 8.

, in Fig. 1, one deck n type stratified film is set here, one deck p type stratified film is set as p type nitride-based semiconductor, but also can in territory, n lateral areas and territory, p lateral areas, 2 layers or above stratified film be set respectively as n type nitride-based semiconductor.For example, if the GaN layer 5 of above-mentioned non-doping is made stratified film as described below, described stratified film is that the intermediate layer that constitutes from the lower floor that substrate one side begins the nitride-based semiconductor by non-doping is constituted, by the nitride-based semiconductor of the n type impurity that mixed and stacked gradually by the upper strata that the nitride-based semiconductor of non-doping constitutes forms, will further improve luminous power output, Vf and anti-electrostatic pressure characteristic, thus preferred.Like this, when in territory, n lateral areas, having two kinds of n type stratified films, as long as any number of plies than p type stratified film in these two kinds of n type stratified films is howed.

At first, stratified film is described.

In the present embodiment 6, n type stratified film 6 as preferred composition, can be enumerated Al as long as constitute by forming different at least two kinds or above nitride-based semiconductors _zGa _1-zN (0≤z＜1) [first nitride semiconductor film] and In _pGa _1-pThese two kinds of compositions of N (0＜p＜1) [second nitride semiconductor film]

As the preferred composition of first nitride semiconductor film, represent that the z value in the chemical formula of above-mentioned first nitride semiconductor film is more little, crystallinity is just good more, and more preferably the z value is shown as 0, i.e. GaN.

In addition, as the preferred composition of second nitride semiconductor film, it is 0.5 or following In that the p value in the chemical formula of above-mentioned second nitride semiconductor film of expression is arranged _pGa _1-pN, more preferably the p value is 0.1 or following In _pGa _1-pN.

In the present invention, as the preferred compositions of first nitride semiconductor film and second nitride semiconductor film, can enumerate first nitride semiconductor film and be GaN, second nitride semiconductor film and be the x value and be 0.5 or following In _xGa _1-xThe combination of N.

In addition, at least form one deck or above first nitride semiconductor film and second nitride semiconductor film respectively by the n type stratified film 6 that constitutes of forming as described above, add up to two-layer or above or 3 layers or more than, be preferably respectively stacked at least two-layer or more than, add up to stacked 4 layers or more than; Be preferably respectively stacked at least 7 layers or more than, add up to stacked 14 layers or more than.

The upper limit of the stacked number of plies of first nitride semiconductor film and second nitride semiconductor film has no particular limits, but will for example 500 layers or below.If surpass 500 layers, the stacked time is just oversize, and trivial operations, the characteristic of element also have the tendency that descends slightly.

The thickness that constitutes the individual layer nitride semiconductor layer of n type stratified film 6 has no particular limits, but has at least a kind of thickness of nitride semiconductor layer of individual layer to be in the two or more nitride semiconductor layers

Or below, be preferably Or below, more preferably

Or below.

Like this, the thickness of the individual layer nitride semiconductor layer by will constituting n type stratified film 6 is done very thinly, and stratified film has just formed superlattice structure, and the crystallinity of stratified film improves, and therefore the tendency that improves power output is just arranged.

At n type stratified film 6 is when being made of first nitride semiconductor film and second nitride semiconductor film, has at least a side thickness to be

Or below, be preferably

Or below, most preferably be

Or below.

The thickness of at least one side in first nitride semiconductor film and second nitride semiconductor film is

Or during following thin layer, the thickness of the nitride semiconductor layer of individual layer is in elasticity critical film thickness or following respectively, and crystallinity is good.When having improved on the crystalline nitride semiconductor layer at this and then regrowth when playing thickness and being elasticity critical film thickness or following nitride-based semiconductor, its crystallinity also will be good.Thus, the crystallinity of first and second nitride semiconductor films as its result, has been improved the crystallinity of n type stratified film 6 integral body along with stacked and improve.Like this, because the crystallinity of n type stratified film 6 integral body becomes good, the luminous power output of element has just improved.

As the preferred thickness of first nitride semiconductor film and second nitride semiconductor film, be that the both is

Or below, be preferably

Or below, most preferably be

Or below.

When both thickness of first and second nitride semiconductor films that constitute n type stratified film 6 all is

Or when following, the thickness of the nitride semiconductor layer of individual layer just becomes elasticity critical film thickness or following, and compares with the situation of thick film growth, can grow the good nitride-based semiconductor of crystallinity.

In addition, all be made as when thickness first and second nitride semiconductor films of n type stratified film 6

Or when following, just stratified film has become superlattice structure, crystallinity becomes well, if grow active layer on the good superlattice structure of this crystallinity, then n type stratified film 6 will play the effect of resilient coating, the active layer of just can crystallinity growing well.

Total film thickness as n type stratified film 6 has no particular limits, but is generally

Be preferably

More preferably

When thickness was in this scope, crystallinity was good, and the power output of element improves.

The formation position of n type stratified film 6 has no particular limits, join with active layer 7 and form or leave with active layer 7 and form can, be preferably n type stratified film 6 and join with active layer 7 and form.

Join and when forming at n type stratified film 6 and active layer 7, as constituting with the initial rete of active layer 7, being the nitride semiconductor layer of the n type stratified film 6 that joins of trap layer or barrier layer, both can be first nitride semiconductor film, also can be second nitride semiconductor film.Constituting first nitride semiconductor film of n type stratified film 6 and the lamination order of second nitride semiconductor film like this has no particular limits.That is, can be stacked since first nitride-based semiconductor, with the first nitride semiconductor bundle; Perhaps stacked since first nitride-based semiconductor, with the second nitride semiconductor bundle; Perhaps stacked since second nitride-based semiconductor, with the first nitride semiconductor bundle; In addition, also can be stacked since second nitride semiconductor film, with the second nitride semiconductor bundle.

In Fig. 1, n type stratified film 6 joins with active layer 7 and forms, but as mentioned above, leaves and when forming at n type stratified film 6 and active layer 7, between n type stratified film 6 and active layer 7, also can form the layer that constitutes by other n type nitride-based semiconductor.

In the present embodiment 6, constitute the nitride semiconductor layer of the individual layer of n type stratified film 6, for example first and second nitride semiconductor films both can be non-doping, the n type that also can mix impurity.

In the present embodiment 6, so-called non-doping refers to the subjective not state of impurity expressly, for example, owing to the situation of impurity is sneaked in the diffusion of adjacent nitride semiconductor layer, also is referred to as non-doping in the present invention.The impurity concentration of the impurity of sneaking in addition, distribution gradient mostly in rete by diffusion.

Under the situation that the individual layer nitride semiconductor layer that constitutes n type stratified film 6 is made up of first nitride semiconductor film and second nitride semiconductor film, first and second nitride semiconductor films can the both be non-doping both, also can both's Doped n-type impurity, perhaps also can be in any one impurity.

Doped n-type impurity in any one of first nitride semiconductor film and second nitride semiconductor film, perhaps, both's Doped n-type impurity and concentration difference in the adjacent nitride semiconductor layer, this is referred to as modulation doping, by modulation doping, have the tendency of easy raising power output.

In addition, when in first nitride semiconductor film and second nitride semiconductor film, two sides all during Doped n-type impurity, the concentration of the impurity in the adjacent individual layer nitride semiconductor layer can be different, also can be identical, and preferred different.

In order to improve crystallinity, most preferably be non-doping, secondly be that an adjacent side is the modulation doping of non-doping, secondly be the modulation doping that adjacent two sides mix again.

In addition, when in first nitride semiconductor film and second nitride semiconductor film all during Doped n-type impurity, the impurity concentration height of either party rete can.

Impurity concentration during to Doped n-type impurity has no particular limits, but generally is adjusted into 5 * 10 ²¹/ cm ³Or below, be preferably 1 * 10 ²⁰/ cm ³Or below, as under be limited to 5 * 10 ¹⁶/ cm ³As be higher than 5 * 10 ²¹/ cm ³, the crystallinity of nitride semiconductor layer will worsen, otherwise, then have the tendency that power output reduces.This also is like this under the situation of modulation doping.

In the present invention, preferably select IV family, VI family elements such as Si, Ge, Sn, S as n type impurity, and then preferably use Si, Sn.

Next, p type stratified film 8 is described.

In the present embodiment 6, p type stratified film 8 as preferred composition, can be enumerated Al so long as constitute and get final product by forming different at least two kinds or above nitride-based semiconductors _xGa _1-xN (0＜x＜1) [the 3rd nitride semiconductor film] and In _yGa _1-yThese two kinds of compositions of N (0≤y＜1) [tetrazotization thing semiconductor film].

As the preferred composition of the 3rd nitride semiconductor film, the x value of chemical formula that is above-mentioned the 3rd nitride semiconductor film of expression is 0.5 or following Al _xGa _1-xN.If x surpasses 0.5, then have the tendency that crystallinity worsens, is easy to generate crackle.

In addition, as the preferred composition of tetrazotization thing semiconductor film, the y value that is the chemical formula of above-mentioned expression tetrazotization thing semiconductor film is 0 GaN.When the y value is 0, have the tendency that can easily grow the good stratified film of whole crystallinity.

In the present embodiment 6,, can enumerate the 3rd nitride semiconductor film and be the x value and be 0.5 or following Al as the preferred compositions of the nitride-based semiconductor that constitutes n type stratified film 8 _xGa _1-xN, tetrazotization thing semiconductor film are the combination of GaN.

In addition, at least form one deck or above the 3rd nitride semiconductor film and tetrazotization thing semiconductor film respectively by the p type stratified film 8 that constitutes of forming as described above, add up to two-layer or above or 3 layers or more than, preferred stacked at least respectively two-layer or more than, add up to stacked 4 layers or more than.

The upper limit of the stacked number of plies of the 3rd nitride semiconductor film and tetrazotization thing semiconductor film has no particular limits, if but consider the factor such as manufacturing process, element characteristic of stacked time etc., for example can enumerate 100 layers or below.

Total film thickness as p type stratified film 8 has no particular limits, but is generally

Be preferably

More preferably

In addition, in the present invention,, just have the Vf that makes element easily, the tendency that threshold value reduces in the thickness of above-mentioned scope if p type stratified film 8 forms with thin thickness.

The thickness that constitutes the individual layer nitride semiconductor layer of p type stratified film 8 has no particular limits, but the thickness of the individual layer nitride semiconductor layer of at least one side's of two kinds or above nitride semiconductor layer nitride semiconductor layer is generally Or below, be preferably

Or below, more preferably

Or below.

Like this, the thickness of the individual layer nitride semiconductor layer by will constituting p type stratified film 8 is done very thinly, stratified film has just become superlattice structure, the crystallinity of stratified film is improved, therefore under the situation of having added p type impurity, can obtain the p layer that carrier concentration is big, resistivity is little, the Vf of element and threshold value have the tendency of easy reduction.Like this, just can obtain very high luminous power output with power consumption seldom.

When p type stratified film 8 is formed by the 3rd nitride semiconductor film and tetrazotization thing semiconductor film, have at least a side thickness to be

Or below, be preferably

Or below, most preferably be

Or below.The thickness of at least one side in the 3rd nitride semiconductor film and tetrazotization thing semiconductor film is

Or during following thin layer, the thickness of the nitride semiconductor layer of individual layer all is elasticity critical film thickness or following, and it is good that crystallinity becomes.When having improved on the crystalline nitride semiconductor layer at this and then regrowth thickness when being elasticity critical film thickness or following nitride-based semiconductor, its crystallinity has just become better.Thus, the crystallinity of third and fourth nitride semiconductor film is along with stacked and improve, and as a result of, the whole crystallinity of p type stratified film 8 has been improved.Like this, because the whole crystallinity of p type stratified film 8 improves, under the situation of having added p type impurity, can obtain the p type layer that carrier concentration is big, resistivity is little, the Vf of element, threshold values have the tendency of easy reduction.So, just can obtain very high luminous power output with very low power consumption.

The preferred thickness of the 3rd nitride semiconductor film and tetrazotization thing semiconductor film is generally the both and is

Or below, be preferably

Or below, most preferably be

Or below.

When the thickness both of third and fourth nitride semiconductor film that constitutes p type stratified film 8 is

In addition, both thickness when third and fourth nitride semiconductor film of p type stratified film 8 all is Or when following, stratified film just becomes superlattice structure, and crystallinity becomes well, and the Vf of element, threshold value etc. are easy to reduce, and is being preferred improving aspect the luminous power output.

The formation position of p type stratified film 8 has no particular limits, and can join with active layer 7 and form, and also can leave and form with active layer 7, is preferably p type stratified film 8 and joins with active layer 7 and form.When p type stratified film 8 and active layer 7 join and when forming, improve luminous power output easily, thus preferred.

Join and when forming at p type stratified film 8 and active layer 7, as constituting with the initial rete of active layer 7, being the nitride semiconductor layer of the p type stratified film 8 that joins of trap layer or barrier layer, both can be the 3rd nitride semiconductor film, also can be tetrazotization thing semiconductor film.Constituting the 3rd nitride semiconductor layer of p type stratified film 8 and the lamination order of tetrazotization thing semiconductor film like this has no particular limits.That is, can be stacked since the 3rd nitride semiconductor film, finish with the 3rd nitride semiconductor film; Perhaps stacked since the 3rd nitride semiconductor film, finish with tetrazotization thing semiconductor film; Perhaps stacked since tetrazotization thing semiconductor film, finish with the 3rd nitride semiconductor film; In addition also can be stacked since tetrazotization thing semiconductor film, finish with tetrazotization thing semiconductor film.

In Fig. 1, p type stratified film 8 joins with active layer 7 and forms, but as mentioned above, leaves and when forming at p type stratified film 8 and active layer 7, between p type stratified film 8 and active layer 7, also can form the rete that constitutes by other p type nitride-based semiconductors.

In addition, in the present embodiment 6, the 3rd nitride semiconductor film and tetrazotization thing semiconductor film can two sides all be non-doping, also can be in either party doped p type impurity, also can be in two sides doped p type impurity all.

The third and fourth nitride semiconductor film both who constitutes p type stratified film 8 is under the situation of non-doping, and the thickness of p type stratified film 8 is generally 0.1 μ m or following, is preferably

Or below, and then be preferably

Or below.When thickness surpasses 0.1 μ m, just be difficult to injected hole in active layer, have the tendency of the luminous power output of easy reduction.In addition, when thickness surpasses 0.1 μ m, make the tendency of the resistance value rising of non-doping rete in addition.

In addition, when carrying out the modulation doping of impurity in either party of third and fourth nitride semiconductor film, have the tendency of the luminous power output of easy raising.In addition, when modulation doping, obtain the high p layer of carrier concentration easily, thus preferred.

In addition, in both of third and fourth nitride semiconductor film, all during doped p type impurity, compare with the situation of having only doped p type impurity, owing to can further increase the concentration of charge carrier, so Vf is low, thus preferred.Under the situation of third and fourth nitride semiconductor film both doped p types impurity, the impurity concentration between the adjacent nitride semiconductor layer can be identical, but be preferably difference (modulation doping).

In the present embodiment 6, when doped p type impurity in p type stratified film 8,, preferably select II family elements such as Mg, Zn, Cd, Be, Ca as p type impurity, preferably use Mg, Be.

Under the situation of doped p type impurity, the concentration of impurity is adjusted into 1 * 10 ²²/ cm ³Or below, be preferably 5 * 10 ²⁰/ cm ³Or below.As be higher than 1 * 10 ²²/ cm ³, the crystallinity of nitride semiconductor layer can worsen, and just has the tendency that reduces luminous power output.Lower limit to the doping of doped p type impurity has no particular limits, but is generally 5 * 10 ¹⁶/ cm ³Or more than.

Below, each layer of the structure that forms other elements except that n type stratified film 6 shown in Fig. 1 and p type stratified film 8 described, but the present invention only limits to this.

As substrate 1, can in addition also have spinelle (MgAl in order to C face, R face or A face sapphire as interarea ₂O ₄) such insulating properties substrate, and SiC (containing 6H, 4H, 3C), Si, ZnO, semiconductor substrates such as GaAs, GaN.

As resilient coating 2, can enumerate by Ga _dAl _1-dThe nitride-based semiconductor that N (condition is that d is in the scope of 0＜d≤1) constitutes, the proportion of composing that is preferably Al is more little, and crystalline improvement is remarkable more, more preferably the resilient coating 2 that is made of GaN.

The thickness of resilient coating 2 is adjusted into 0.002～0.5 μ m, is preferably 0.005～0.2 μ m, more preferably the scope of 0.01～0.02 μ m.When the thickness of resilient coating 2 was in above-mentioned scope, the crystal habit of nitride-based semiconductor was good, and the crystallinity of the nitride-based semiconductor of growth can improve on resilient coating 2.

The growth temperature of resilient coating 2 is adjusted into 200～900 ℃, is preferably 400～800 ℃ scope.When growth temperature is in above-mentioned scope, can grow well-crystallized's polycrystal, as crystal seed, can make the crystallinity of the nitride-based semiconductor of growth on resilient coating 2 good with this polycrystal, thereby preferred.In addition, the resilient coating 2 that growth is got up under such low temperature also can omit according to the kind of substrate, the method for growth etc.

As the GaN layer 3 of non-doping, make it in temperature, for example 900 ℃～1100 ℃ growths down higher, by In than the resilient coating that grows out earlier 2 _fAl _gGa _1-f-gN (0≤f, 0≤g, f+g≤1) constitutes, though its composition needn't be particularly limited, is preferably GaN, g value and is 0.2 or following Al _gGa _1-gN so just obtains the few nitride semiconductor layer of crystal defect easily.In addition, thickness also needn't be particularly limited, and to grow than the thicker thick film of resilient coating, generally grows with 0.1 μ m or above thickness.

As the n type contact layer 4 that the GaN by the Si that mixed constitutes, the same with the GaN layer 3 of non-doping, can be by InfAl _gGa _1-f-gN (0≤f, 0≤g, f+g≤1) constitutes, though its composition needn't be particularly limited, is preferably GaN, g value and is 0.2 or following Al _gGa _1-gN so just obtains the few nitride semiconductor layer of crystal defect easily.Also needn't be particularly limited for thickness, but because be the rete that forms the n electrode, so preferably grow with 0.1 μ m or above thickness.Further, preferably the high concentration of the degree that the crystallinity of nitride-based semiconductor worsens is mixed with the concentration of n type impurity, that is, preferably 1 * 10 ¹⁸/ cm ³～5 * 10 ²¹/ cm ³Scope in mix.

As the GaN layer 5 of non-doping, with top the same, can be by In _fAl _gGa _1-f-gN (0≤f, 0≤g, f+g≤1) constitutes, though its composition needn't be particularly limited, is preferably GaN, g value and is 0.2 or following Al _gGa _1-gN or f value are 0.1 or following In _fGa _1-fN so just obtains the few nitride semiconductor layer of crystal defect easily.GaN layer by this non-doping of growing, different with the situation of one deck under direct growth one-tenth on the n type contact layer 4 of the high concentration impurities of having mixed, the crystallinity of bottom is also good, therefore just growth easily of the n type stratified film 6 of next growth, and then when growth active layer 7 on n type stratified film, it is easier to grow, and the crystallinity change is good, thereby preferred.Like this, if stacked n type contact layer 4 that constitutes by the nitride-based semiconductor of the high concentration impurities of having mixed and the non-Doped GaN layer 5 that constitutes by the nitride-based semiconductor of non-doping of lamination then on the GaN layer 3 of the non-doping that the nitride semiconductor layer by non-doping constitutes, and then make the structure of stacked said n type stratified film 6, when making the LED element, just have the tendency that Vf is descended.In addition, be under the situation of non-doping at n type stratified film 6, can omit the GaN layer 5 of non-doping.

In addition, in the present embodiment 6, also can be identical with embodiment 5, replace above-mentioned non-Doped GaN layer 5, make the stratified film that the upper strata 305c by the 305a of lower floor of non-doping, mixed the intermediate layer 305b of n type impurity, non-doping constitutes.

Stratified film constitutes by at least three layers, from substrate one side, be respectively non-doping the 305a of lower floor, the intermediate layer 305b of n type impurity, the upper strata 305c of non-doping have mixed.At other retes that can also have on the stratified film except that the above-mentioned 305a of lower floor～upper strata 305c.In addition, stratified film both can join with active layer, also can have other layers between it and active layer.

Nitride-based semiconductor as constituting the above-mentioned 305a of lower floor～upper strata 305c can use by In _gAl _hGa _1-g-hThe nitride-based semiconductor of the various compositions of N (0≤g＜1,0≤h＜1) expression.Preferably can enumerate the nitride-based semiconductor of forming that is made of GaN, in addition, the composition of each of stratified film layer both can be identical, also can be different.

The thickness of stratified film has no particular limits, and is generally Be preferably More preferably

When the thickness of stratified film is in above-mentioned scope, can realize the optimization of Vf and the raising of anti-electrostatic pressure characteristic, thereby preferred.

The preferred thickness of suitably adjusting the 305a of lower floor, intermediate layer 305b and upper strata each layer of 305c of adjustment of thickness of stratified film with thickness of above-mentioned scope is so that the gross thickness of stratified film is in above-mentioned scope.

Constitute the not special restriction of thickness of the 305a of lower floor, intermediate layer 305b and upper strata each layer of 305c of stratified film, but since they in stratified film stacked position for the difference that influences of the various characteristics of element, so pay special attention to each layer characteristic big with the element function relation, the thickness of fixing any two-layer rete, make the thickness phasic Chang of that remaining one deck then, measure the thickness in the good scope of characteristic, and then, determine the scope of thickness by adjusting the thickness of each layer.

Though each of stratified film directly do not influence anti-electrostatic pressure characteristic layer separately, but become stratified film by each layer combined, do as a wholely, various element characteristics are improved, simultaneously, particularly luminous power output and anti-electrostatic pressure characteristic there is significant improvement.

The thickness of the 305a of lower floor of non-doping is generally

Be preferably

More preferably When the thickness progressive additive of the 305a of lower floor of non-doping, anti-electrostatic pressure characteristic also rises gradually, but

Near Vf sharply rises; On the other hand, when the thickness attenuate, Vf is also along with reduction, but that anti-electrostatic pressure characteristic is fallen is much lower, less than

The time, along with the decline of anti-electrostatic pressure, stock utilization has the tendency that descends significantly.In addition, owing to consider that upper strata 305a has improved the influence of the crystalline decline of the n side contact layer 4 that contains n type impurity, so preferably grow with the crystalline thickness that is improved as good degree.

The thickness of intermediate layer 305b of n type impurity of having mixed is generally

Be preferably

More preferably

The intermediate layer 305b of this impurity that mixed be make charge carrier concentration fully, luminous power output is had the layer of bigger effect, if do not form this rete, then have the tendency that luminous power output significantly descends.If thickness surpasses

Just have the tendency that luminous power output drops to the degree that is difficult to become commodity significantly.On the other hand, when the thickening of the thickness of intermediate layer 305b, anti-electrostatic pressure characteristic is good, if but thickness less than Just have the tendency that anti-electrostatic pressure characteristic descends significantly.

The thickness of the upper strata 305c of non-doping is generally

Be preferably

More preferably

The upper strata 305c of this non-doping joins with active layer in first stratified film or is the most approaching and form, with the much relations that prevented of leakage current, if but the thickness of upper strata 305c less than Leakage current just has the tendency of increase.In addition, the thickness as upper strata 305c surpasses

The time, the tendency that anti-electrostatic pressure characteristic descends with regard to there being Vf to rise.

As mentioned above, thick to the 305a of lower floor～each tunic of upper strata 305c, what note is the element characteristic that is subjected to more influences because of the thickness change of each layer, further, when the combination 305a of lower floor, intermediate layer 305b and upper strata 305c, the various characteristics that makes element all is good, particularly luminous power output and anti-electrostatic pressure characteristic are improved, by stipulating the thickness of each layer, just can obtain good luminous power output and good anti-electrostatic pressure characteristic, can reach the further lifting of the reliability of commodity.

In addition, the thick combination of each tunic of stratified film, the various conditions such as shape of the composition variation of the active layer that can change by the kind because of emission wavelength, electrode, LED element are suitably adjusted, to obtain the best effect.Suitably make up by thickness, can make the combination relevant performance thick, reach good luminous power output compared with the past and good anti-electrostatic pressure characteristic with each tunic with above-mentioned scope.

Each layer 305a, the 305b of formation stratified film, the composition of 305c are so long as use In _mAl _nGa _1-m-nThe composition of N (0≤m＜1,0≤n＜1) expression get final product, and the composition of each layer can be identical, also can difference, the ratio of In and Al of being preferably little composition, the rete that constitutes by GaN more preferably.

The doping of the n type impurity among the intermediate layer 5b of above-mentioned Doped n-type impurity has no particular limits, and generally containing concentration is 3 * 10 ¹⁸/ cm ³Or more than, be preferably 5 * 10 ¹⁸/ cm ³Or more than.As the upper limit of n type impurity, though have no particular limits, the boundary of the degree that can too not worsen as crystallinity is preferably 5 * 10 ²¹/ cm ³Or below.When the impurity concentration in the intermediate layer of first stratified film is in above-mentioned scope, be preferred from the aspect of the reduction of the raising of luminous power output and Vf.

What select as n type impurity is IVB family, the group vib element of periodic tables such as Si, Ge, Se, S, O, preferably with Si, Ge, S as n type impurity.

In addition, on the interface of stratified film, in the scope of the function that does not hinder each layer and element, each layer can use by two kinds of retes of double as.

Next,, can enumerate the nitride-based semiconductor that contains In at least, be preferably and have the In of containing as active layer 7 _jGa _1-jThe single quantum of the trap layer of N (0≤j＜1) or the nitride-based semiconductor of multi-quantum pit structure.

The stacked order of active layer 7 can be to begin stackedly to finish with the trap layer with the trap layer, can be to begin stackedly to finish with barrier layer with the trap layer, in addition, also can begin stackedly to finish with the trap layer with barrier layer, and stacked order needn't be particularly limited.Thickness as the trap layer generally is adjusted into

Or below, be preferably Or below, and then be preferably Or below.When than

When thicker, the tendency that is difficult to improve power output will be arranged.On the other hand, the thickness of barrier layer generally is adjusted into Or below, be preferably

Or below, most preferably be

Or below.

Next, same as described above as the p type contact layer 9 that the GaN by the Mg that mixed constitutes, can be by In _fAl _gGa _1-f-gN (0≤f, 0≤g, f+g≤1) constitutes, though its composition is not done special the qualification, is preferably GaN, is easy to so just to obtain the few nitride semiconductor layer of crystal defect, and is easy to obtain good Ohmic contact with the p electrode material.

In addition, employed in the present invention p electrode and n electrode have no particular limits, and can use known electrode etc. in the past, for example can be set forth in the electrode described in the embodiment.

Embodiment

Below, embodiments of the invention are described, but the present invention is not limited in these following embodiment.

Embodiment 1

Embodiment 1 is the embodiment relevant with embodiment of the present invention 1 as shown in Figure 1.

In present embodiment 1, will be placed in the reaction vessel of MOVPE by the substrate 1 that sapphire (C face) made, Yi Bian feed hydrogen,, carry out the cleaning of substrate Yi Bian make the temperature of substrate rise to 1050 ℃, form following each layer then.In addition, substrate 1 can also use R face except that the C face or A face as the sapphire of interarea, can also use spinelle (MgAl ₂O ₄) such insulating properties substrate, and SiC (containing 6H, 4H, 3C), Si, ZnO, semiconductor substrates such as GaAs, GaN.

(first resilient coating 2)

Then, temperature is dropped to 510 ℃, with hydrogen as carrier gas, with ammonia and TMG (trimethyl gallium) as unstrpped gas, on substrate 1 with approximately

Thickness grow into the resilient coating 202 that forms by GaN.Also can omit this low temperature first resilient coating 2 of growth down in addition according to the kind of substrate, growing method etc.

(second resilient coating 3)

After first resilient coating 2 grew into, a stop supplies TMG was elevated to 1050 ℃ with temperature.After reaching 1050 ℃, use TMG, ammonia equally, grow into second resilient coating 3 that the GaN by non-doping forms with the thickness of 1 μ m as unstrpped gas.Second resilient coating 3 is that it can be by In in the high temperature higher than first resilient coating 2 of growth earlier, for example 900 ℃～1100 ℃ growth down _xAl _yGa _1-x-yN (0≤x, 0≤y, x+y≤1) constitutes, though its composition needn't be particularly limited, is preferably GaN, x value and is 0.2 or following Al _xGa _1-xN so just is easy to obtain the few nitride semiconductor layer of crystal defect.In addition, thickness needn't be particularly limited, and is to grow than the thickness of buffering bed thickness, to grow with 0.1 μ m or above thickness usually.

(n side contact layer 4)

Then, use TMG, ammonia as unstrpped gas down equally at 1050 ℃, as foreign gas, growing by the concentration of having mixed with the thickness of 3 μ m is 3 * 10 with silane gas ¹⁹/ cm ³The n side contact layer that forms of the GaN of Si.This n side contact layer 4 is also the same with second resilient coating 3, can be by In _xAl _yGa _1-x-yN (0≤x, 0≤y, x+y≤1) constitutes, though its composition needn't be particularly limited, is preferably GaN, x value and is 0.2 or following Al _xGa _1-xN so just is easy to obtain the few nitride semiconductor layer of crystal defect.Thickness needn't be particularly limited, but because be the layer that forms the n electrode, grows so be preferably with 0.1 μ m or above thickness.Further, preferably the high concentration of the degree that worsens with the crystal property that does not make nitride-based semiconductor is come Doped n-type impurity, preferably with 1 * 10 ¹⁸/ cm ³～5 * 10 ²¹/ cm ³Scope mix.

(three buffer layer 5)

Then, a stop supplies silane gas, under 1050 ℃, similarly with

Thickness grow the three buffer layer 5 that the GaN by non-doping constitutes.This three buffer layer 5 also can be by In _xAl _yGa _1-x-yN (0≤x, 0≤y, x+y≤1) constitutes, though its composition needn't be particularly limited, is preferably GaN, x value and is 0.2 or following Al _xGa _1-xN or y value are 0.1 or following In _yGa _1-yN so just is easy to obtain the few nitride semiconductor layer of crystal defect.By growing into the GaN layer of this non-doping, different with direct growth active layer on the n side contact layer 4 of high concentration impurities of having mixed, the crystallinity of substrate part is good, so the nitride-based semiconductor that is easy to grow and then will grows.Like this, if make three-decker, described three-decker is on second resilient coating 3 that the nitride semiconductor layer by non-doping constitutes, the stacked last n side contact layer 4 that constitutes by the nitride-based semiconductor of the high concentration n type impurity that mixed, the then stacked last three buffer layer 5 that is made of the nitride-based semiconductor (also comprising n side stratified film) of non-doping forms, when making the LED element, just have the tendency that is easy to make Vf decline.In addition, be under the situation of non-doping at n side stratified film 6, can omit three buffer layer 5.

(n side stratified film 6)

Next, reduce the temperature to 800 ℃, use TMG, TMI, ammonia, grow into In by non-doping _0.03Ga _0.97N constitutes, thickness is

First nitride semiconductor film, then elevated temperature, growth thickness is thereon

, second nitride semiconductor film that constitutes by GaN.Then, repeat above operation repeatedly, be with thickness

Grow by mutual stacked separately 10 layers the n side stratified film that superlattice structure constitutes with the first+the second order.

(active layer 7)

Next, with

Thickness grow the barrier layer that the GaN by non-doping constitutes, then, continue to make temperature to remain on 800 ℃, use TMG, TMI, ammonia, with

Thickness grow In by non-doping _0.4Ga _0.6The trap layer that N constitutes.Then, according to barrier layer+trap layer+barrier layer+trap layer ... the order of+barrier layer is alternately stacked with 5 layers of barrier layer and 4 layers of trap layer, just grows into by gross thickness to be

The active layer 7 that constitutes of multi-quantum pit structure.Though it is stacked that active layer 7 begins with barrier layer, but also can begin stackedly to finish with the trap layer with the trap layer, in addition, when beginning with the trap layer to finish with barrier layer, also can begin stackedly to finish with the trap layer with barrier layer, stacked order needn't be done special qualification.Thickness as the trap layer generally is adjusted into

Or below, be preferably

Or below, and then be preferably

Or below.If surpass

The tendency that is difficult to improve power output will be arranged.On the other hand, the thickness of barrier layer generally is adjusted into

Or below, be preferably

Or below, most preferably be

Or below.

(p side stratified film 8)

Next, use TMG, TMA, ammonia, Cp2Mg (two luxuriant magnesium), with Thickness grow by mixing 5 * 10 ¹⁹/ cm ³The p type Al of Mg _0.05Ga _0.95The 3rd nitride semiconductor film that N constitutes then, stops Cp2Mg, TMA, with

Thickness grow the tetrazotization thing semiconductor film that the GaN by non-doping constitutes.Then, repeat above operation repeatedly, with

Thickness grow by the p side stratified film 8 that constitutes with the stacked respectively 4 layers superlattice in the 3rd+the 4th sequence alternate ground.

(p side contact layer 9)

Then, under 1050 ℃, use TMG, ammonia, Cp2Mg, with Thickness grow by having mixed 1 * 10 ²⁰/ cm ³The p side contact layer 208 that constitutes of the p type GaN of Mg.P side contact layer 208 also can be by In _xAl _yGa _1-x-yN (0≤x, 0≤y, x+y≤1) constitutes, though its composition needn't be particularly limited, preferably adopts GaN, the few nitride semiconductor layer of so easy acquisition crystal defect, and obtain easily and p electrode material good Ohmic contact.

Reaction makes temperature drop to room temperature, and then wafer (wafer) is placed in the reaction vessel again after finishing, and in nitrogen atmosphere, anneals under 700 ℃, makes the further low resistanceization of p type layer.

After the annealing, wafer is taken out from reaction vessel, on the surface of the p of the top one deck side contact layer 9, form the mask of reservation shape, begin to carry out etching from the p side contact layer with RIE (reactive ion etching) device, as shown in Figure 1, the surface of n side contact layer 4 is exposed.

After the etching, the formation thickness is on the almost whole surface of the p of the superiors side contact layer

The light transmission p electrode 10 that contains Ni and Au, on this p electrode 10, form thickness again and be the p pad electrode 11 that the Au that is used by bonding of 0.5 μ m constitutes.On the other hand, on the surface of the n side contact layer 4 that comes out owing to etching, form the n electrode 12 that contains W and Al, just become the LED element.

This LED element can show the pure green light of 520nm under forward voltage 20mA, Vf has only 3.2V, compares with the LED element of in the past multi-quantum pit structure, and Vf has reduced 0.8V nearly, and power output has improved more than the twice.Therefore, can obtain under 10mA, to have and in the past the LED element LED of equal characteristic roughly.

In the present embodiment, second nitride semiconductor film that constitutes n side stratified film is made of GaN, but also can be by other In _xAl _yGa _1-x-yN (0≤x, 0≤y, x+y≤1), be preferably the few InGaN of ratio of components first nitride-based semiconductor of In and constitute.In addition, the tetrazotization thing semiconductor film that constitutes p side stratified film is made of GaN, but also can be by other In _xAl _yGa _1-x-yN (0≤x, 0≤y, x+y≤1), be preferably the few AlGaN of ratio of components the 3rd nitride-based semiconductor of Al and constitute.

In addition, the formation of LED element in the past is to stack gradually following each rete to form on first resilient coating that is made of GaN: second resilient coating that is formed by the GaN of non-doping, the n side contact layer that forms by the GaN of doping Si, by the active layer that the multi-quantum pit structure identical with embodiment 1 forms, the doping of individual layer the Al of Mg _0.1Ga _0.9The N layer, the p side contact layer that forms by the GaN of the Mg that mixed.

Embodiment 2

Embodiment 2 is LED elements as shown in Figure 2.In the present embodiment,, nor p side stratified film 8 is made superlattice structure except growth regulation three buffer layer 5 not, with

Thickness grow by having mixed 5 * 10 ¹⁹/ cm ³The p type Al of Mg _0.1Ga _0.9Outside the p side coating layer 108 that the N layer is constituted, other are all identical with embodiment 1 and make the LED element, and equally under 20mA, Vf is 3.3V, has shown very good value then, and power output has also improved more than 1.8 times.

Embodiment 3

In the present embodiment, except when growing n side stratified film 6, it is 1 * 10 that second nitride semiconductor film is made the concentration of having mixed ¹⁸/ cm ³The GaN of Si, in addition, p side stratified film is not made superlattice structure, with Thickness grow by having mixed 5 * 10 ¹⁹/ cm ³The p type Al of Mg _0.1Ga _0.9Outside the p side coating layer 108 that the N layer is constituted, other are all identical with embodiment 1 and make the LED element, at this moment can obtain to have the LED element with the almost equal characteristic of embodiment 2.

Embodiment 4

In the present embodiment, except when the growth n side stratified film 6, first nitride semiconductor film made mixed 1 * 10 ¹⁸/ cm ³The In of Si _0.03Ga _0.97Rete, second nitride semiconductor film made mixed 5 * 10 ¹⁸/ cm ³The GaN of Si, in addition, p side stratified film is not made superlattice structure, and makes by having mixed 5 * 10 ¹⁹/ cm ³The p type Al of Mg _0.1Ga _0.9Outside the p side coating layer 108 that the N layer constitutes, other are all identical with embodiment 1 and make the LED element, and at this moment Vf is 3.4V under 20mA, and power output and comparing have in the past shown the good characteristic more than 1.5 times.

Embodiment 5

In the present embodiment, except growth regulation three buffer layer 5 not, and when growth p side stratified film 8, grow in tetrazotization thing semiconductor film and mixed 1 * 10 ¹⁹/ cm ³The p type GaN layer of Mg outside, other are all the same with embodiment 1 and make the LED element, at this moment can obtain almost to have with embodiment 1 the LED element of equal characteristic.

Embodiment 6

In the present embodiment, except growth regulation three buffer layer 5 not, and when growth p side stratified film 8, alternately laminated each two-layer Al by non-doping _0.1Ga _0.9The thickness that N constitutes is

The 3rd nitride semiconductor film and by the thickness that the GaN of non-doping constitutes be

Tetrazotization thing semiconductor film, total film thickness is

Outside, other are all identical with embodiment 1 and when making the LED element, can obtain roughly the LED element of characteristic similarly to Example 4.

Embodiment 7

Present embodiment has likened change as described below to mutually with embodiment 1.That is, when growth n side stratified film 6, at first grow

The In by non-doping _0.03Ga _0.97First nitride semiconductor film that N forms then grows

Second nitride semiconductor film that forms of the GaN by non-doping.Then, grow

The In of non-doping _0.03Ga _0.97The rete that N forms, regeneration grows

The GaN layer of non-doping, then, grow

The In of non-doping _0.03Ga _0.97The N layer.The growth of first nitride semiconductor film is reduced

Until only growth

Till.First rete and second rete is so alternately laminated, and each stacked 10 layers of each retes grow the n side multilayer film that is formed by superlattice structure, add up to thickness to be

On the other hand, when growth p side stratified film 8, with

Thickness grow by having mixed 5 * 10 ¹⁹/ cm ³The p type Al of Mg _0.05Ga _0.95The 3rd nitride semiconductor film that N forms, then with

Thickness grow the tetrazotization thing semiconductor film that the GaN by non-doping forms, then make the p type In of the Mg of the same concentration of having mixed again _0.05Ga _0.95The N layer growth arrives

The GaN layer growth of non-doping is arrived

The growth of the 3rd nitride semiconductor film is reduced

Until only growth Till.Tertiary membrane layer and the 4th rete is so alternately laminated, and each stacked 5 layers of each retes grow the p side multilayer film that is formed by superlattice structure, add up to thickness to be

In the present embodiment, except the above part, other are all identical with embodiment 1 and obtain the LED element, like this, just can obtain to have the element with the roughly equal characteristic of the LED element of embodiment 1.In addition, in the present embodiment, though only changed the thickness of first nitride semiconductor film that constitutes n side stratified film 6, the thickness that changes second nitride semiconductor film also can obtain identical effect.In addition, though only changed the thickness of the 3rd nitride semiconductor film that constitutes p side stratified film 8, the thickness that changes tetrazotization thing semiconductor film also can obtain identical effect.

Embodiment 8

Present embodiment has likened change as described below to mutually with embodiment 1.That is, when growth n side stratified film 6, make In by non-doping _0.03Ga _0.97First nitride semiconductor film that N forms grows into

Second nitride semiconductor film that GaN by non-doping is formed grows into

Then, the big slightly InGaN layer growth of mol ratio of In is arrived The GaN layer growth of non-doping is arrived

Like this, the composition of the In of first nitride semiconductor film is increased gradually and grow, make first rete and second rete alternately laminated, each stacked 10 layers of each retes, last, making ground floor is In _0.3Ga _0.7N thereby grow total film thickness is

N side stratified film.

On the other hand, when growth p side stratified film 8, with

Thickness grow the tetrazotization thing semiconductor film that the GaN by non-doping forms, then making the Mg of the same amount of mixing again but the many slightly p type AlGaN layer growths of composition of Al arrive

The GaN layer growth of non-doping is arrived

Like this, the composition of the Al of the 3rd nitride semiconductor film is increased gradually and grow, make tertiary membrane layer and the 4th rete alternately laminated, each stacked 4 layers of each retes, last, make the 3rd layer to be Al _0.2Ga _0.8N thereby grow total film thickness is

P side multilayer film.

In the present embodiment, except the above part, other are all identical with embodiment 1 and obtain the LED element, like this, just can obtain to have the element with the roughly equal characteristic of the LED element of embodiment 1.In addition, in the present embodiment, though only changed the composition of the III family element of first nitride semiconductor film that constitutes n side multilayer film 6, but at the nitride-based semiconductor of second nitride semiconductor film being made ternary mixed crystal or quarternary mixed crystal, change the composition of its III family element, also can obtain same effect.In addition, though above only changed the composition of the III group element of the 3rd nitride semiconductor film that constitutes p side stratified film 8, but at the nitride-based semiconductor of tetrazotization thing semiconductor film being made ternary mixed crystal or quarternary mixed crystal, change the composition of its III family element, also can obtain same effect.

Embodiment 9

In the present embodiment, except p side stratified film 8 not being made stratified film, but with

Thickness growth by having mixed 5 * 10 ¹⁹/ cm ³The p type Al of Mg _0.1Ga _0.9Beyond the p side coating layer 108 that the N layer constitutes, other are all identical with embodiment 7 and make the LED element, like this, can obtain to have the LED element with the roughly equal characteristic of embodiment 2.

Embodiment 10

Thickness growth by having mixed 5 * 10 ¹⁹/ cm ³The p type Al of Mg _0.1Ga _0.9Beyond the p side coating layer 108 that the N layer constitutes, other are all identical with embodiment 8 and make the LED element, like this, can obtain to have the LED element with the roughly equal characteristic of embodiment 2.

Embodiment 11

In the present embodiment, except the variation of the composition of the In that makes first nitride-based semiconductor that constitutes n side multilayer film opposite with embodiment 8, and the variation of composition of Al that makes the 3rd nitride-based semiconductor that constitutes p side multilayer film also opposite beyond, promptly, except the composition that makes the In in first nitride semiconductor film few more near active layer more, make the composition of the Al in the 3rd nitride semiconductor film leave more active layer few more beyond, other are all the same with embodiment 8 and make the LED element, like this, just can obtain to have LED element with the roughly equal characteristic of embodiment 8.

Embodiment 12

In the present embodiment, except when growing n side stratified film 6, make In by non-doping _0.2Ga _0.8First nitride semiconductor film that N forms grows into

Then make In by non-doping _0.05Ga _0.95Second nitride semiconductor film that N forms grows into

Outside, other are all identical with embodiment 1 and make the LED element, like this, just can obtain to have the LED element with the roughly equal characteristic of the LED element of embodiment 1.

Embodiment 13

In the present embodiment, except when growing p side stratified film 8, make Al by the Mg that mixed _0.05Ga _0.95First nitride semiconductor film that N forms grows into

Then make In by non-doping _0.1Ga _0.9Second nitride semiconductor film that N forms grows into Outside, other are all identical with embodiment 1 and making the LED element, like this, just can obtain to have the LED element with the roughly equal characteristic of the LED element of embodiment 1.

Embodiment 14

In the present embodiment, except when growing n side stratified film 6, make In by non-doping _0.03Ga _0.97First nitride semiconductor film that N forms grows into

Second nitride semiconductor film that GaN by non-doping is formed grows into

Promptly grow into except the thickness that makes first nitride semiconductor film

Embodiment 15

In the present embodiment, except when growing p side stratified film 8, make Al by the Mg that mixed _0.05Ga _0.95The thickness of first nitride semiconductor film that N forms grows into

Outside, other are all identical with embodiment 1 and make the LED element, like this, just can obtain to have the element with the roughly equal characteristic of the LED element of embodiment 1.

Embodiment 16

The nitride semiconductor device of embodiments of the invention 16 is a laser diode as shown in Figure 3, have active layer 56 between territory, p lateral areas 80 and territory, n lateral areas 70.

The laser diode of present embodiment 16 is to make by each layer below growth on the thick GaN substrate 50 of 80 μ m:

(1) by the thick doping of 3 μ m the formed n type of the GaN GaN layer 52 of Si;

The thick In of (2) 0.1 μ m _0.1Ga _0.9N layer 53;

(3) by In _xGa _1-xThe n side coating layer 54 of the superlattice structure that N/n type GaN forms;

(4) the mixed thick n type GaN photoconductive layer 55 of 0.1 μ m of Si;

(5) In _0.4Ga _0.6N/In _0.02Ga _0.98The active layer 56 of N multi-quantum pit structure;

(6) the mixed thickness of Mg is

Al _0.2Ga _0.8N layer 57;

(7) the mixed thickness of Mg is the p type GaN photoconductive layer 58 of 0.1 μ m;

(8) by Al _yGa _1-yThe p side coating layer 59 of the superlattice structure that N/p type GaN forms;

(9) the mixed thickness of Mg is the p type GaN contact layer 60 of 0.05 μ m.

In addition, n side coating layer 54 is to be by thickness

Doping GaN layer and the thickness of Si be

The In of non-doping _xGa _1-xN layer, each 240 layers of alternately laminated formation show n type conductivity on the whole.Here, in n side coating layer 54, the In of non-doping _xGa _1-xThe N film is along with near active layer, and the amount of In increases, and changes successively in 0.01～0.3 scope by the value that makes x, just makes the composition gradual change of n side coating layer 54.

In addition, active layer 56 is thickness alternately to be set respectively be

4 layers of In of Si have mixed _0.15Ga _0.85N trap layer and thickness are

The In of Si has mixed _0.02Ga _0.98The N barrier layer forms.

And then p side coating layer 59 is to be by thickness

Doping GaN layer and the thickness of Mg be

The Al of non-doping _yGa _1-yN layer, each 120 layers of alternately laminated formation show p type conductivity on the whole.Here, in p side coating layer 59, the Al of non-doping _yGa _1-yThe N film is along with near active layer, and the amount of Al reduces, and changes successively in 0.01～0.2 scope by the value that makes y, just makes the composition gradual change of p side coating layer 59.

In present embodiment 16, after forming each layer of above-mentioned (1)～(9),, on p type contact layer 60, form by Ni/Au and constitute by etching, wide 3 μ m, grow 450 μ m, be carinate p lateral electrode 61.On the n type GaN of a side that is positioned at ridge layer, form the n lateral electrode that constitutes by Ti/Al.

In addition, in the laser diode of embodiment 16, by on the both ends of the surface of ridge, forming two couples of TiO ₂/ SiO ₂, make the reflection coefficient of both ends of the surface become 50%.

In the semiconductor laser diode of the embodiment 16 that makes as described above, can obtain the continuous oscillation under the little room temperature of threshold current.

As mentioned above, even make stratified film (superlattice layer) leave and form, also can obtain good result such shown in present embodiment 16 from active layer.

Embodiment 17

Embodiment 17 is embodiments relevant with embodiment shown in Figure 42.

In the present embodiment, will be placed in the reaction vessel of MOVPE,,, carry out cleaning substrate Yi Bian the temperature of substrate is risen to 1050 ℃ Yi Bian feed hydrogen by the substrate 1 that sapphire (C face) made.

(resilient coating 102)

Then, temperature is dropped to 510 ℃, as carrier gas, use ammonia and TMG (trimethyl gallium), on substrate 1, grow thickness and be approximately as unstrpped gas with hydrogen

The resilient coating 102 that forms by GaN.

(the GaN layer 103 of non-doping)

After resilient coating 102 growths, a stop supplies TMG is elevated to 1050 ℃ with temperature.After reaching 1050 ℃, use TMG, ammonia as unstrpped gas equally, growing thickness is the GaN layer 103 of the non-doping of 1.5 μ m.

(n side contact layer 4)

Then, under 1050 ℃, use ammonia and TMG (trimethyl gallium) equally as unstrpped gas, with silane gas as foreign gas, grow thickness 2.25 μ m, by having mixed 4.5 * 10 ¹⁸/ cm ³The n side contact layer 4 that forms of the GaN of Si.

(n side first stratified film 105)

Then, a stop supplies silane gas under 1050 ℃, uses ammonia and TMG, grows thickness and is

The GaN layer of non-doping; Then, under same temperature, add silane gas again, grow thickness and be

, mixed 4.5 * 10 ¹⁸/ cm ³The GaN layer of Si.Like this, just grow by thickness and be

, the A layer that constitutes by non-Doped GaN and GaN with the Si that mixed, thickness is The a pair of rete that constitutes of B layer.Then, with stacked 25 layers of paired rete, its thickness is reached

Thereby grow n side first stratified film 105 that the stratified film by superlattice structure constitutes.

(n side second stratified film 106)

Then, under same temperature, the second nitride semiconductor film 106b that the GaN by non-doping is constituted grows into

Then, reduce the temperature to 800 ℃, use TMG, TMI, ammonia, grow In by non-doping _0.13Ga _0.87N constitutes, thickness is

The first nitride semiconductor film 106a.Then, repeat above operation repeatedly, each alternately stacked 10 layers of the orders with the second+the first grow at last

The second nitride semiconductor film 106b that constitutes by GaN, thereby grow into that the multilayer film of superlattice structure constitutes, thickness be

N side second stratified film 106.

(active layer 7)

Then, growing thickness is

The barrier layer that constitutes of the GaN by non-doping, then, make temperature remain on 800 ℃, use TMG, TMI, ammonia, grow thickness and be The In by non-doping _0.4Ga _0.6The trap layer that N constitutes.Then, according to barrier layer+trap layer+barrier layer+trap layer ... the order that+barrier layer is such, 5 layers of barrier layer and 4 layers of trap layer are alternately stacked, thereby grow into gross thickness be

, active layer 7 that multi-quantum pit structure constitutes.

(p side multilayer film coating layer 108)

Then, under 1050 ℃, use TMG, TMA, ammonia, Cp2Mg (two luxuriant magnesium), grow thickness and be

, by having mixed 1 * 10 ²⁰/ cm ³The p type Al of Mg _0.2Ga _0.8The 3rd nitride semiconductor film 108a that N constitutes; Then, make temperature drop to 800 ℃, use TMG, TMI, ammonia, Cp2Mg, grow thickness and be

, by having mixed 1 * 10 ²⁰/ cm ³The In of Mg _0.03Ga _0.97The tetrazotization thing semiconductor film 108b that N constitutes.Then, repeat above operation repeatedly, each alternately stacked 5 layers of the orders with the 3rd+the 4th grow thickness at last

The 3rd nitride semiconductor film 108a, thereby grow into that the multilayer film of superlattice structure is formed, thickness be

P side stratified film coating layer 108.

(p side GaN contact layer 9)

Then, under 1050 ℃, use TMG, ammonia, Cp2Mg, grow thickness and be , by having mixed 1 * 10 ²⁰/ cm ³The p side contact layer 9 that constitutes of the p type GaN of Mg.

Reaction drops to room temperature with temperature after finishing, and wafer is placed in the reaction vessel again, in nitrogen atmosphere, anneals under 700 ℃, makes the further low resistanceization of p type layer.

After the annealing, wafer is taken out from reaction vessel, on the surface of the p of the top one deck side contact layer 9, form the mask of reservation shape, begin to carry out etching from the p side contact layer with RIE (reactive ion etching) device, as shown in Figure 4, the surface of n side contact layer 4 is exposed.

After the etching, the formation thickness is on the almost whole surface of the p side contact layer that is positioned at the superiors

, the light transmission p electrode 11 that contains Ni and Au, forming thickness again on this p electrode 11 is 0.5

The p pad electrode 11 that Au μ m, that used by bonding constitutes.On the other hand, formation contains the n electrode 12 of W and Al on the surface of the n side contact layer 4 that comes out owing to etching, thereby produces the LED element.

Under forward voltage 20mA, this LED element shows the pure green light of 520nm, and Vf has only 3.5V, compares with the LED element of in the past multi-quantum pit structure, and Vf has reduced 1.0V nearly, and power output has improved more than the twice.Therefore, can obtain under 10mA, to have with in the past the LED of the roughly equal characteristic of LED element.

In addition, LED element in the past is to stack gradually following each rete to form on first resilient coating that is made of GaN: second resilient coating that is formed by the GaN of non-doping, the n side contact layer that forms by the GaN of doping Si, by the p side active layer that the multi-quantum pit structure identical with embodiment 12 forms, the doping of individual layer the Al of Mg _0.1Ga _0.9The N layer, the p side contact layer that forms by the GaN of the Mg that mixed.

Embodiment 18

In the present embodiment, except the active layer among the embodiment 17 7 has been done the following variation, other are all identical with embodiment 17 and be made into the LED element.

(active layer 7)

Then, growing thickness is The barrier layer that constitutes of the GaN by non-doping, then, make temperature remain on 800 ℃, use TMG, TMI, ammonia, grow thickness and be

The In by non-doping _0.3Ga _0.7The trap layer that N constitutes.Then, according to barrier layer ten trap layer+barrier layers+trap layer+... the order that+barrier layer is such, 7 layers of barrier layer and 6 layers of trap layer are alternately stacked, thereby grow by gross thickness be

The active layer 7 that constitutes of multi-quantum pit structure.

The LED element that is obtained shows the ethereal blue coloured light of 470nm when the positive direction electric current is 20mA, can obtain the good result identical with embodiment 17.

Embodiment 19

(active layer 7)

Then, growing thickness is

The barrier layer that constitutes of the GaN by non-doping, then, make temperature remain on 800 ℃, use TMG, TMI, ammonia, grow thickness and be

The In by non-doping _0.3Ga _0.7The trap layer that N constitutes.Then, according to barrier layer+trap layer+barrier layer+trap layer+... the order that+barrier layer is such, 6 layers of barrier layer and 5 layers of trap layer are alternately stacked, thereby grow by gross thickness be

The active layer 7 that constitutes of multi-quantum pit structure.

Embodiment 20

(active layer 7)

Then, growing thickness is

The barrier layer that constitutes of the GaN by non-doping, then, make temperature remain on 800 ℃, use TMG, TMI, ammonia, grow thickness and be The In by non-doping _0.35Ga _0.65The trap layer that constitutes.Then, according to barrier layer+trap layer+barrier layer+trap layer+... the order that+barrier layer is such, 7 layers of barrier layer and 6 layers of trap layer are alternately stacked, thereby grow by gross thickness be

The active layer 7 that constitutes of multi-quantum pit structure.

The LED element that is obtained shows the bluish-green coloured light of 500nm when the positive direction electric current is 20mA, can obtain the good result identical with embodiment 17.

Embodiment 21

(active layer 7)

Then, growing thickness is

The In by non-doping _0.35Ga _0.65The trap layer that N constitutes.Then, according to barrier layer+trap layer+barrier layer+trap layer+... the order that+barrier layer is such, 4 layers of barrier layer and 3 layers of trap layer are alternately stacked, thereby grow by gross thickness be

The active layer 7 that constitutes of multi-quantum pit structure.

When the positive direction electric current was 20mA, the LED element that obtained showed the bluish-green coloured light of 500nm, can obtain the good result identical with embodiment 17.

Embodiment 22

In the present embodiment, except n side second stratified film 6 of not growing, other are all identical with embodiment 17 and be made into the LED element.

Though the LED element that is obtained is more weaker slightly than element characteristic and the luminous power output of embodiment 17, compare with LED element in the past, still have good luminous power output.

Embodiment 23

In the present embodiment, except the p side multilayer film coating layer 8 among the embodiment 17 has been done the following variation, other are all identical with embodiment 17 and be made into the LED element.

(p side monofilm coating layer 18)

Under 1050 ℃ of temperature, use TMG, TMA, ammonia, Cp2Mg (two luxuriant magnesium), grow thickness and be

, by mixing 1 * 10 ²⁰/ cm ³The p type Al of Mg _0.16Ga _0.84The p side monofilm coating layer that N constitutes.

Though the LED element that is obtained is coating layer not to be made superlattice structure but with the monofilm layer growth, but the textural association by each layer with other together, though performance is more a little bit poorer slightly than embodiment 1, can obtain almost equal good result.In addition, if make the individual layer rete, its manufacturing process just can be simplified much than making stratified film, thereby preferred.

Embodiment 24

In the present embodiment, except first stratified film 105 of the n side among the embodiment 17 has been done the following variation, other are all identical with embodiment 17 and be made into the LED element.

(n side first stratified film 105)

Growing thickness is , by the A layer that the GaN of non-doping constitutes, grow thickness then and be

, by having mixed 1 * 10 ¹⁸/ cm ³The Al of Si _0.1Ga _0.9The B layer that N constitutes is folded 20 layers layer by layer with paired A layer and B then, thereby grow thickness is

N side first stratified film 105.

The LED element that is obtained has the roughly equal characteristic with embodiment 17, can obtain good result.

Embodiment 25

In the present embodiment, except the n side contact layer 4 among the embodiment 17 has been done the following variation, other are all identical with embodiment 17 and be made into the LED element.

(n side contact layer 4)

Under 1050 ℃, with ammonia and TMG as unstrpped gas, with silane gas as foreign gas, grow thickness and be 6 μ m thick, by having mixed 4.5 * 10 ¹⁸/ cm ³The n side contact layer 4 that forms of the GaN of Si.

Embodiment 26

Embodiment 26 is embodiments relevant with embodiment shown in Figure 53.

In present embodiment 26, at first will be placed in the reaction vessel by the substrate 1 that sapphire (mode that with the surface is the C face is cut) makes, with hydrogen the gas in the container is fully replaced, then, one side feeds hydrogen, and one side is elevated to 1050 ℃ with the temperature of substrate 1, carries out the cleaning of substrate.In addition, in substrate 1, can also use R face except that the C face or A face, can also use spinelle (MgAl as the sapphire of interarea ₂O ₄) such insulating properties substrate, and SiC (containing 6H, 4H, 3C), Si, ZnO, semiconductor substrates such as GaAs, GaN.

(resilient coating 202)

, the resilient coating 202 that forms by GaN.

(a n side nitride semiconductor layer 203)

After resilient coating 202 grew into, a stop supplies TMG was elevated to 1050 ℃ with temperature.After reaching 1050 ℃, use ammonia and TMG (trimethyl gallium) as unstrpped gas equally, growing that GaN by non-doping forms, thickness is the n side nitride semiconductor layer 203 of 5 μ m.The one n side nitride semiconductor layer 203 preferably under the high temperature higher than resilient coating 202, for example 900 ℃～1100 ℃ growths down; Except GaN, also can be by In _xAl _yGa _1-x-yN (0≤x, 0≤y, x+y≤1) constitutes, and preferably using GaN or x value is 0.2 or following Al _xGa _1-xN so just is easy to obtain the few nitride semiconductor layer of crystal defect.In addition, preferably, grow with 0.1 μ m or above thickness usually to grow than the thickness of buffering bed thickness.Because this layer non-doped layer normally, so its character and intrinsic semiconductor are approaching, and its resistivity is greater than 0.2 Ω cm, but also can be with the n type impurity such as amount doping Si, Ge that also lack than the 2nd n side nitride semiconductor layer, thereby make resistivity decreased.

(the 2nd n side nitride semiconductor layer 204)

Then, under 1050 ℃ of temperature, use TMG, ammonia, grow thickness and be

Non-Doped GaN layer, then, feed silane gas again, grow thickness and be

Doping 1 * 10 ¹⁹/ cm ³The GaN layer of Si, then, stop the Si that mixes, regrowth goes out thickness and is The GaN layer of non-doping.Like this, just grow a pair of rete that is made of A layer and B layer, described A layer is to be by thickness

The GaN layer of non-doping constitute, described B layer is to be by thickness Doping the GaN layer of Si constitute.Stacked then this a pair of rete just grows the 2nd n side nitride semiconductor layer 204 that constitute, thickness 1 μ m by the GaN of modulation doping.

(the 3rd n side nitride semiconductor layer 205)

Then, a stop supplies silane gas under 1050 ℃, similarly grows thickness and is

, the 3rd n side nitride semiconductor layer 205 that constitutes by the GaN of non-doping.Except that GaN, the 3rd n side nitride semiconductor layer 205 also can be by In _xAl _yGa _1-x-yN (0≤x, 0≤y, x+y≤1) constitutes, though its composition needn't be particularly limited, is preferably the x value and is 0.2 or following Al _xGa _1-xN, perhaps the y value is 0.1 or following In _yGa _1-yN so just is easy to obtain the few nitride semiconductor layer of crystal defect.If growing InGaN when growth contains the nitride-based semiconductor of Al on it, just can prevent to crack in containing the nitride semiconductor layer of Al.

(active layer 7)

Then, temperature is transferred to 800 ℃, changes carrier gas into nitrogen, use TMG, TMI (trimethyl indium), ammonia, grow thickness and be

The In of non-doping _0.4Ga _0.6The N layer, thus grow active layer 7 with single quantum.In addition, this one deck also can be the multi-quantum pit structure with the trap layer that is made of InGaN.

(p side coating layer 108)

Then, temperature is risen to 1050 ℃, use TMG, TMA, ammonia Cp2Mg (two luxuriant magnesium), grow thickness and be

, by having mixed 1 * 10 ²⁰/ cm ³The p type Al of Mg _0.1Ga _0.9The rete that N constitutes; Then, use TMG, ammonia, Cp2Mg, grow thickness and be

, by having mixed 1 * 10 ¹⁹/ cm ³The rete that constitutes of the GaN of Mg.Below, by alternately repeating same operation, forming total film thickness is the p side coating layer of the super lattice structure layers formation of 0.8 μ m.

(p side contact layer 208)

Next, under 800 ℃, grow thickness and be

, by the In of non-doping _0.1Ga _0.9First nitride semiconductor film that N constitutes; Then, stop supplies TMI grows thickness and is , by having mixed 1 * 10 ²⁰/ cm ³Second nitride semiconductor film that constitutes of the GaN of Mg.Alternately laminated then, grow into total film thickness and be

P side contact layer 208.

Reaction is reduced to room temperature with temperature, and then in nitrogen atmosphere, wafer is placed in the reaction vessel after finishing, and anneals under 700 ℃, makes the further low resistanceization of each layer of p side.

After the annealing, wafer is taken out from reaction vessel, on the surface of the p of the superiors side contact layer 208, form the mask of reservation shape, use RIE (reactive ion etching) to begin to carry out etching then from the p side contact layer, as shown in Figure 5, the surface of the 2nd n side nitride semiconductor layer 204 is exposed.

After the etching, the formation thickness is on almost whole of the p side contact layer that is positioned at the superiors

, the p electrode 10 of the light transmission that contains Ni and Au, on this p electrode 10, form thickness then and be the p pad electrode 10 that the Au that is used by bonding of 0.5 μ m constitutes.On the other hand, on the surface of the 2nd n side nitride semiconductor layer 204 that exposes by etching, form the n electrode 12 that contains W and Al.At last, in order to protect the surface of p electrode 10, forming by SiO in mode shown in Figure 5 ₂After the dielectric film 12 that constitutes, with wafer-separate, become the square LED element of 350 μ m by scriber.

This LED element is under 20mA, and forward voltage is 3.2V, sends the green light of 520nm, the Vf under the 20mA can be reduced by 0.2～0.3V, can make power output improve 10% or more than.In addition, make 100, measure 20mA forward voltage Vf down at the LED element shown in the embodiment 21, its result, in the scope that is distributed in 3.2V～3.3V of their Vf, the degree that disperses is minimum.

Embodiment 27

In the present embodiment, except when growing the p side contact layer, with the In of non-doping _0.1Ga _0.9The N layer with mixed 1 * 10 ²⁰/ cm ³GaN stacked of Mg come out of order outside, other are all identical with embodiment 26 and be made into the LED element.

Embodiment 28

In the present embodiment, except when the growth p side contact layer, change the composition of second nitride-based semiconductor into In _0.05Ga _0.95Outside the N, other are all identical with embodiment 26 and be made into the LED element.

Embodiment 29

In the present embodiment, except when the growth p side contact layer, second nitride semiconductor film made mixed 1 * 10 ²⁰/ cm ³The In of Mg _0.05Ga _0.95Outside the N layer, other are all identical with embodiment 26 and be made into the LED element.

Embodiment 30

In the present embodiment, except when the growth p side contact layer, second nitride semiconductor film made mixed 1 * 10 ²⁰/ cm ³The Al of Mg _0.05Ga _0.95Outside the N layer, other are all identical with embodiment 26 and be made into the LED element.

Embodiment 31

In the present embodiment, except when growing the p side contact layer, in first nitride semiconductor film, mixed 1 * 10 ²⁰/ cm ³Mg outside, other are all identical with embodiment 26 and be made into the LED element.

Embodiment 32

In the present embodiment, except when growing the p side contact layer, use by having mixed 1 * 10 ²⁰/ cm ³The In of Mg _0.1Ga _0.9First nitride semiconductor film that N constitutes replaces the In by non-doping _0.1Ga _0.9First nitride semiconductor film that the N layer constitutes, and use by having mixed 1 * 10 ¹⁹/ cm ³Second nitride semiconductor film that constitutes of the GaN of Mg replace by having mixed 1 * 10 ²⁰/ cm ³Second nitride semiconductor film that constitutes of the GaN of Mg, and first nitride semiconductor film formed topmost outside one deck, other are all identical with embodiment 26 and be made into the LED element.

Embodiment 33

In the present embodiment, except forming the p side contact layer 208 in following mode, other are all identical with embodiment 26 and be made into the LED element.

That is, under 800 ℃ temperature, the formation thickness is

, by the In of non-doping _0.1Ga _0.9First nitride semiconductor film that N constitutes; Then, reduce TMI gradually, form and form on thickness direction gradually from In _0.1Ga _0.9N changes to the rete of the composition gradual change of GaN; At TMI is after 0, grows thickness to be

, by having mixed 1 * 10 ²⁰/ cm ³Second nitride semiconductor film that constitutes of the GaN of Mg.Then, increase TMI again gradually, form composition and on thickness direction, be varied to In from GaN gradually _0.1Ga _0.9The rete of the composition gradual change of N; Afterwards, forming thickness again is

, by the In of non-doping _0.1Ga _0.9First nitride semiconductor film that N constitutes.Repeat this operation then, all become 10 layers separately, grow p side contact layer 208 thus up to first nitride semiconductor film and second nitride semiconductor film.

LED element among the above embodiment 27～33 is also the same with embodiment 26, compares with example in the past, can obtain good luminescent characteristic.

In addition, in the p side contact layer that is made of InGaN in the past, because InGaN is in the short zone of wavelength, the absorption of light is more, be colored as yellow so exist this p side contact layer, the light wavelength that produces in active layer is moved such problem to the long lateral deviation of wavelength.Yet, because p side contact layer of the present invention is superlattice structure, therefore compare with the p side contact layer that in the past the InGaN by individual layer constitutes, can reduce the absorptivity of the short light of wavelength.Thereby p side contact layer of the present invention can prevent to the skew of long direction of light wavelength, thereby can also improve the transmitance of light.

Fig. 7 is the curve chart with respect to the transmitance of the light of different wave length of the multilayer film of the superlattice structure of the present invention that is made of GaN and InGaN of expression.This multilayer film be with GaN (

) and InGaN (

) alternately laminated 30 cycles form, have and mixed 4 * 10 ¹⁸/ cm ³The p type rete of carrier concentration of Mg.In addition, in Fig. 7,, also shown In by individual layer in order to compare _0.15Ga _0.85The light transmission rate of example in the past that N (thickness 0.12 μ m) constitutes.As shown in Figure 7, can see, the multilayer film of superlattice structure of the present invention is obviously different with the absorptivity with respect near the light the wavelength 400nm of monofilm of example in the past, and the transmitance with respect near the light the 400nm of the multilayer film of superlattice structure of the present invention wants much excellent.In addition, the multilayer film of the superlattice structure of the present invention shown in Fig. 7 all is 0.5 Ω cm with the electricalresistivity separately of monofilm of example in the past.In addition, the transmitance among Fig. 7 is represented is to be 100% relative value with sapphire light transmission rate.

Embodiment 34

Embodiment 34 is the embodiment that are associated with embodiment shown in Figure 85.

In embodiment 34, at first, will place in the reaction vessel of MOVPE by the substrate 1 that sapphire (C face) made, Yi Bian feed hydrogen,, substrate is cleaned Yi Bian make the temperature of substrate rise to 1050 ℃.

(resilient coating 102)

, the resilient coating 102 that forms by GaN.

(the GaN layer 103 of non-doping)

After growing into resilient coating 102, a stop supplies TMG, and temperature is elevated to 1050 ℃.After reaching 1050 ℃, use ammonia, TMG as unstrpped gas equally, growing thickness is the GaN layer 103 of the non-doping of 1.5 μ m.

(n side contact layer 4)

Then, under 1050 ℃, use ammonia, TMG equally as unstrpped gas, with silane gas as foreign gas, grow thickness and be 2.25 μ m, by having mixed 4.5 * 10 ¹⁸/ cm ³The n side contact layer 4 that forms of the GaN of Si.

(n side first stratified film 305)

, the 305a of lower floor that constitutes by the GaN of non-doping; Then, under same temperature, add silane gas again, grow thickness and be

, by having mixed 4.5 * 10 ¹⁸/ cm ³The intermediate layer 305b that constitutes of the GaN layer of Si; Then, a stop supplies silane gas grows thickness and is under same temperature , the upper strata 305c that constitutes by the GaN of non-doping; So just grow constitute by three layers, total film thickness is

First stratified film 305.

(n side second stratified film 306)

Then, under same temperature, second nitride semiconductor film that the GaN by non-doping is constituted grows into

Then, reduce the temperature to 800 ℃, use TMG, TMI, ammonia, grow thickness and be , by the In of non-doping _0.13Ga _0.87Second nitride semiconductor film that constitutes.Then, repeat above operation, stacked with the first+the second sequence alternate ground, each stacked 10 layers, grow thickness at last

Second nitride semiconductor film that constitutes by GaN, thereby grow into constitute by the superlattice structure multilayer film, thickness is

N side second stratified film 306.

(active layer 7)

Then, growing thickness is

, the barrier layer that constitutes by the GaN of non-doping; Then, continue to make temperature to remain on 800 ℃, use TMG, TMI, ammonia, grow thickness and be

, by the In of non-doping _0.4Ga _0.6The trap layer that N constitutes.Then, according to barrier layer+trap layer+barrier layer+trap layer ... the order that+barrier layer is such, 5 layers of barrier layer and 4 layers of trap layer are alternately stacked, just grow into gross thickness and be

, the active layer 7 that constitutes by multi-quantum pit structure.

(p side multilayer film coating layer 8)

, by having mixed 1 * 10 ²⁰/ cm ³The p type Al of Mg _0.2Ga _0.8The 3rd nitride semiconductor film that N constitutes; Then, make temperature drop to 800 ℃, use TMG, TMI, ammonia, Cp2Mg, grow thickness and be

, by having mixed 1 * 10 ²⁰/ cm ³The In of Mg _0.03Ga _0.97The tetrazotization thing semiconductor film that N constitutes.Then, repeat above operation, stacked separately 5 layers with the 3rd+the 4th sequence alternate ground, grow thickness at last and be

The 3rd nitride semiconductor film, thereby grow into thickness

The p side stratified film coating layer 8 formed of the multilayer film by superlattice structure.

(p side GaN contact layer 9)

Then, under 1050 ℃, use TMG, ammonia, Cp2Mg, grow thickness and be

, by having mixed 1 * 10 ²⁰/ cm ³The p side contact layer 9 that constitutes of the p type GaN of Mg.

Reaction drops to room temperature with temperature, and then in nitrogen atmosphere, wafer is placed in the reaction vessel again after finishing, and anneals under 700 ℃, makes the further low resistanceization of p type rete.

After the annealing, wafer is taken out from reaction vessel, on the surface of the p side contact layer 9 that is positioned at the top one deck, form the mask of reservation shape, begin to carry out etching from p side contact layer one side with RIE (reactive ion etching) device, as shown in Figure 8, the surface of n side contact layer 4 is exposed.

, the light transmission p electrode 11 that contains Ni and Au, and then to form thickness on this p electrode 11 be the p pad electrode 11 that Au 0.5 μ m, that used by bonding constitutes.On the other hand, on the surface of the n side contact layer of exposing by etching 4, form the n electrode 12 that contains W and Al, thereby form the LED element.

This LED element shows the pure green light of 520nm under positive direction electric current 20mA, Vf is 3.5V, compares with the LED element of in the past multi-quantum pit structure, and Vf has reduced 1.0V nearly, and power output has improved more than the twice.Therefore, can obtain under 10mA, to have LED with the roughly equal characteristic of LED element in the past.Further, from each electrode of the n layer of LED element and p layer, boost voltage is measured the anti-electrostatic potential performance of the LED that is obtained gradually on opposite direction, at this moment can access the good result more than 1.5 times in the past.

In addition, the formation of LED element in the past is to stack gradually following each rete to form on first resilient coating that is made of GaN: second resilient coating that is formed by the GaN of non-doping, the n side contact layer that forms by the GaN of the Si that mixed, by the active layer that the multi-quantum pit structure identical with embodiment 27 forms, the doping of individual layer the Al of Mg _0.1Ga _0.9The N layer, the p side contact layer that forms by the GaN of the Mg that mixed.

Embodiment 35

In the present embodiment, except with active layer 7 has been done the following variation among the embodiment 34, other are all identical with embodiment 34 and be made into the LED element.

(active layer 7)

Then, growing thickness is

, by the In of non-doping _0.3Ga _0.7The trap layer that N constitutes.Then, according to barrier layer+trap layer+barrier layer+trap layer ... the order that+barrier layer is such, 7 layers of barrier layer and 6 layers of trap layer are alternately stacked, just grow into gross thickness and be

, the active layer 7 that constitutes by multi-quantum pit structure.

The LED element that is obtained is sent out the ethereal blue coloured light of 470nm when the positive direction electric current is 20mA, can obtain the 34 same good results with embodiment.

Embodiment 36

(active layer 7)

Then, growing thickness is , the barrier layer that constitutes by the GaN of non-doping; Then, continue to make temperature to remain on 800 ℃, use TMG, TMI, ammonia, grow thickness and be

, by the In of non-doping _0.3Ga _0.7The trap layer that N constitutes.Then, according to barrier layer+trap layer+barrier layer+trap layer ... the order that+barrier layer is such, 6 layers of barrier layer and 5 layers of trap layer are alternately stacked, just grow into gross thickness and be

, the active layer 7 that constitutes by multi-quantum pit structure.

Embodiment 37

(active layer 7)

Then, growing thickness is

, by the In of non-doping _0.35Ga _0.65The trap layer that N constitutes.Then, according to barrier layer+trap layer+barrier layer+trap layer ... the order that+barrier layer is such, 7 layers of barrier layer and 6 layers of trap layer are alternately stacked, just grow into gross thickness and be

, the active layer 7 that constitutes by multi-quantum pit structure.

The LED element that is obtained is sent out the bluish-green coloured light of 500nm when the positive direction electric current is 20mA, can obtain the 34 same good results with embodiment.

Embodiment 38

(active layer 7)

Then, growing thickness is

, by the In of non-doping _0.35Ga _0.65The trap layer that N constitutes.Then, according to barrier layer+trap layer+barrier layer+trap layer ... the order that+barrier layer is such, 4 layers of barrier layer and 3 layers of trap layer are alternately stacked, just grow into gross thickness and be

, the active layer 7 that constitutes by multi-quantum pit structure.

Embodiment 39

In the present embodiment, except not generating n side second stratified film 306, other are all identical with embodiment 34 and be made into the LED element.

The LED element that is obtained is compared with embodiment 34, though element characteristic and luminous power output reduce slightly, anti-electrostatic pressure characteristic is still roughly good similarly to Example 27.

Embodiment 40

In the present embodiment, except with p side multilayer film coating layer 8 has been done among the embodiment 34 following such variation, other are all identical with embodiment 34 and be made into the LED element.

(p side monofilm coating layer 8)

Under 1050 ℃, use TMG, TMA, ammonia, Cp2Mg (two luxuriant magnesium), grow thickness and be

, by having mixed 1 * 10 ²⁰/ cm ³The p type Al of Mg _0.16Ga _0.84The p side monofilm coating layer 8 that N constitutes.

Though not growing into superlattice structure with coating layer, the LED element that is obtained grows into individual layer, but by with other the combination of film layer structure, though performances such as luminous power output are more a bit weaker than embodiment 27, can obtain the almost equal good result of anti-electrostatic pressure characteristic.In addition,, compare with the situation of making stratified film if make individual layer, can simplified manufacturing technique, thereby preferred.

Embodiment 41

In the present embodiment, except first stratified film 305 of the n side among the embodiment 34 has been changed the thickness of each layer in the following way, other are all identical with embodiment 34 and be made into the LED element.

(n side first stratified film 305)

Then, a stop supplies silane gas under 1050 ℃, uses ammonia and TMG, grows thickness and is , the 305a of lower floor that constitutes by the GaN layer of non-doping; Then, under same temperature, add silane gas again, grow thickness and be

, by having mixed 4.5 * 10 ¹⁸/ cm ³The intermediate layer 305b that constitutes of the GaN layer of Si; Then, a stop supplies silane gas grows thickness and is under same temperature

, the upper strata 305c that constitutes by non-Doped GaN; So, just grow constitute by three layers, total film thickness is

First stratified film 305.

The LED element that is obtained has the roughly equal characteristic with embodiment 34, can obtain good result.

Embodiment 42

In the present embodiment, except with n side first stratified film 305 is changed in the following way among the embodiment 41, other are all identical with embodiment 41 and be made into the LED element.

That is, growing thickness is The Al of non-doping _0.1Ga _0.9N is as the 305a of lower floor, grows thickness to be

, mixed 4.5 * 10 ¹⁸/ cm ³The Al of Si _0.1Ga _0.9N is as intermediate layer 305b, grows thickness to be

The Al of non-doping _0.1Ga _0.9N constitutes upper strata 305c.The LED element that is obtained as described above has the roughly equal characteristic with embodiment 41, can obtain good result.

Comparative example 1

In this comparative example, constitute the 305a of lower floor n side first stratified film 305, that constitute by the GaN of non-doping except not forming, other are all identical with embodiment 34 and be made into the LED element.

The LED element that is obtained is compared with embodiment 34, and anti-electrostatic pressure characteristic is significantly low, the value that neither fully meet the demands about the characteristic of leakage current and Vf.

Comparative example 2

In this comparative example, constitute intermediate layer 305b n side first stratified film 305, that constitute by the GaN of the Si that mixed except not forming, other are all identical with embodiment 34 and be made into the LED element.

The LED element that is obtained is compared with embodiment 34, and luminous power output and anti-electrostatic pressure characteristic are significantly low, the value that other characteristic neither fully meet the demands.

Comparative example 3

In this comparative example, constitute upper strata 305c n side first stratified film 305, that constitute by the GaN of non-doping except not forming, other are all identical with embodiment 34 and be made into the LED element.

The LED element that is obtained is compared with embodiment 34, and leakage current increases, the value that other characteristics neither fully meet the demands.

Embodiment 43

Embodiment 43 is embodiments relevant with embodiment of the present invention 6.

(substrate 1)

To place in the reaction vessel of MOVPE by the substrate 1 that sapphire (C face) made,,, substrate is cleaned Yi Bian make the temperature of substrate 1 rise to 1050 ℃ Yi Bian feed hydrogen.

(resilient coating 2)

Then, temperature is dropped to 510 ℃, as carrier gas, use ammonia and TMG (trimethyl gallium), on substrate 1, grow thickness and be approximately as unstrpped gas with hydrogen , the resilient coating 2 that forms by GaN.In addition, according to the kind of substrate and growing method etc., can also dispense first resilient coating 2 that this is grown at low temperatures.

(the GaN layer 3 of non-doping)

After growing into resilient coating 2, a stop supplies TMG is elevated to 1050 ℃ with temperature.After reaching 1050 ℃, use ammonia and TMG as unstrpped gas equally, growing thickness is the GaN layer 3 of the non-doping of 1 μ m.

(n type contact layer 4)

Then, under 1050 ℃, use ammonia and TMG equally as unstrpped gas, with silane gas as foreign gas, grow 3 μ m thick, by having mixed 3 * 10 ¹⁹/ cm ³The n type contact layer that forms of the GaN of Si.

(the GaN layer 5 of non-doping)

Then, a stop supplies silane gas under 1050 ℃, grows thickness in the same way and is The GaN layer 5 of non-doping.

(n type stratified film 6)

Then, reduce the temperature to 800 ℃, use TMG, TMI, ammonia, grow In by non-doping _0.03Ga _0.97N constitutes, and thickness is

Second nitride semiconductor film; Then, improve temperature, grow thickness thereon and be

, first nitride semiconductor film that constitutes by the GaN of non-doping.Repeat above operation then, grow into thickness and be , the n type multilayer film that constitutes by superlattice structure, described superlattice structure is to form for each stacked 10 layers according to the second+the first sequence alternate ground.

(active layer 7)

Then, growing thickness is

, the barrier layer that constitutes by the GaN of non-doping; Then, continue to make temperature to remain on 800 ℃, use TMG, TMI, ammonia, grow thickness and be , by the In of non-doping _0.4Ga _0.6The trap layer that N constitutes.Then, according to barrier layer+trap layer+barrier layer+trap layer ... the order that+barrier layer is such, 5 layers of barrier layer and 4 layers of trap layer are alternately stacked, just grow gross thickness and be

, the active layer 7 that constitutes by multi-quantum pit structure.

(p type stratified film 8)

Then, use TMG, TMA, ammonia, Cp2Mg (two luxuriant magnesium), grow thickness and be

, by having mixed 5 * 10 ¹⁹/ cm ³The p type Al of Mg _0.1Ga _0.9The 3rd nitride semiconductor film that N constitutes.Then, stop Cp2Mg, TMA, grow thickness and be

, the tetrazotization thing semiconductor film that constitutes by the GaN of non-doping.Then, repeat above operation, stacked respectively 4 layers with the sequence alternate ground of the three+the tetrazotization thing semiconductor film, grow thickness at last and be

, the p type stratified film 8 that constitutes by superlattice structure.

(p type contact layer 9)

Then, under 1050 ℃, use TMG, ammonia, Cp2Mg, grow thickness and be , by having mixed 1 * 10 ²⁰/ cm ³The p type contact layer 8 that constitutes of the p type GaN of Mg.

After the annealing, wafer is taken out from reaction vessel, on the surface of the p type contact layer 9 that is positioned at the top one deck, form the mask of reservation shape, install with RIE (reactive ion etching), begin to carry out etching from p type contact layer, as shown in Figure 1, the surface of n type contact layer 4 is exposed.

After the etching, the formation thickness is on the almost whole surface of the p type contact layer that is positioned at the superiors , the light transmission p electrode 10 that contains Ni and Au, forming thickness then on this p electrode 10 is the p pad electrode 11 that Au 0.5 μ m, that used by bonding constitutes.On the other hand, on the surface of the n type contact layer 4 that comes out by etching, form the n electrode 12 that contains W and Al, thereby become the LED element.

This LED element can show the pure green light of 520nm under forward voltage 20mA, Vf is 3.5V, compares with the LED element of in the past multi-quantum pit structure, and Vf has reduced 0.5V nearly, and luminous power output has improved more than the twice.Therefore, can obtain under 10mA, to have with in the past the LED of the roughly equal characteristic of LED element.And then the anti-electrostatic pressure characteristic of the element that is obtained is compared about improvement more than 1.2 times with element in the past.

In addition, the formation of LED element in the past is to stack gradually following each rete to form on first resilient coating that is made of GaN: second resilient coating that is formed by the GaN of non-doping, the n side contact layer that forms by the GaN of the Si that mixed, by the active layer that the multi-quantum pit structure identical with embodiment 1 forms, the doping of individual layer the Al of Mg _0.1Ga _0.9The N layer, the p type contact layer that forms by the GaN of the Mg that mixed.

Embodiment 44

In the present embodiment, except when the growing n-type stratified film 6, first nitride semiconductor film is grown into mixed 1 * 10 ¹⁸/ cm ³The GaN of Si outside, other are all identical with embodiment 43 and be made into the LED element.The element that is obtained has the good element characteristic roughly equal with embodiment 43

Embodiment 45

In the present embodiment, except when the growing n-type stratified film 6, second nitride semiconductor film made mixed 1 * 10 ¹⁸/ cm ³The In of Si _0.03Ga _0.97The N layer is made first nitride semiconductor film and has been mixed 5 * 10 ¹⁸/ cm ³The GaN layer of Si outside, other are all identical with embodiment 43 and be made into the LED element.The LED element that is obtained is when 20mA, and Vf is 3.4V, and power output is higher more than 1.5 times than element in the past, demonstrates excellent characteristic.In addition, anti-electrostatic pressure characteristic is also same good with embodiment 43.

Embodiment 46

In the present embodiment, except when the growing p-type stratified film 8, tetrazotization thing semiconductor film is grown into mixed 1 * 10 ¹⁹/ cm ³The p type GaN of Mg outside, other are all identical with embodiment 43 and be made into the LED element, like this, just can obtain to have the LED element with the roughly equal characteristic of embodiment 43.

Embodiment 47

In the present embodiment, except when the growing p-type stratified film 8, be with thickness

The Al by non-doping _0.1Ga _0.9The 3rd nitride semiconductor film and thickness that N constitutes are

Thereby the tetrazotization thing semiconductor film that constitutes of the GaN by non-doping alternately each stacked two-layer total film thickness that makes be

Outside, other are all identical with embodiment 43 and be made into the LED element, like this, just can obtain to have the LED element with the roughly equal characteristic of embodiment 43.

Embodiment 48

In the present embodiment, replace the GaN layer 5 of non-doping except forming stratified film, and following each layer done outside the following variation, other are all identical with embodiment 43 and manufacture the LED element.

(n side contact layer 4)

Then, under 1050 ℃, use ammonia and TMG equally as unstrpped gas, with silane gas as foreign gas, grow 2.25 μ m thick, by having mixed 6 * 10 ¹⁸/ cm ³The n type contact layer 4 that forms of the GaN of Si.

(stratified film)

, the 305a of lower floor that constitutes by non-Doped GaN; Then, under same temperature, add silane gas again, grow thickness and be

, by having mixed 6 * 10 ¹⁸/ cm ³The intermediate layer 305b that constitutes of the GaN of Si; Then, a stop supplies silane gas grows thickness and is under same temperature

, the upper strata 305c that constitutes by non-Doped GaN; So, just grow form by three layers, total film thickness is

Stratified film.

(n type stratified film 6)

Then, under same temperature, grow thickness and be

, first nitride semiconductor film that constitutes by the GaN of non-doping; Then, reduce the temperature to 800 ℃, use TMG, TMI, ammonia, grow thickness and be

, by the In of non-doping _0.02Ga _0.98Second nitride semiconductor film that N constitutes.Then, repeat above operation, the order according to the first+the second, grows thickness at last by alternately stacked each 10 layers First nitride semiconductor film that constitutes by GaN, thereby grow into that multilayer film by superlattice structure constitutes, thickness be N type stratified film 6.

(p type multilayer film 8)

, by having mixed 5 * 10 ¹⁹/ cm ³The p type Al of Mg _0.2Ga _0.8The 3rd nitride semiconductor film that N constitutes; Then, make temperature drop to 800 ℃, use TMG, TMA, ammonia Cp2Mg, grow thickness and be

, by having mixed 5 * 10 ¹⁹/ cm ³The In of Mg _0.02Ga _0.98The tetrazotization thing semiconductor film that N constitutes.Then, repeat above operation, the order according to the 3rd+the 4th, grows thickness at last and is by alternately each stacked 5 layers

The 3rd nitride semiconductor film, thereby grow into thickness

, the p type stratified film 8 formed by the multilayer film of superlattice structure.

The LED element that is obtained has shown good luminous power output and the Vf roughly equal with embodiment 43, further, from each electrode of the n layer of LED element and p layer, boost voltage is measured the anti-electrostatic pressure characteristic of the LED that is obtained gradually on opposite direction, at this moment can obtain following effect: compare with the element in the past of the comparison that is used as embodiment 43, the result is higher more than 1.5 times than element in the past, and its anti-electrostatic pressure characteristic is also better than embodiment's 43.

In the above-described embodiment, though use the nitride semiconductor luminescent element as the LED element to be illustrated, the present invention is not limited in the LED element, also goes for other light-emitting components such as laser diode element.

In addition, the present invention is not only limited to light-emitting component yet, goes for using nitride-based semiconductor and photo-sensitive cell such as the solar cell that constitutes, optical sensor, perhaps electronic device such as triode, power device yet.

The industry utilizability

As mentioned above, according to the present invention, in nitride-based semiconductor, particularly nitride semiconductor luminescent element, just can under very low electric current, obtain and the power output equal or more than it of LED element in the past, can further improve luminous power output.

In addition, according to the present invention, can also improve anti-electrostatic pressure characteristic, can provide reliability very high nitride semiconductor device, but enlarge the scope of application of application product.

In addition, the present invention is not only limited to light-emitting component, goes for the various electronic devices that photo-sensitive cell, solar cell etc. use nitride-based semiconductor yet.

Claims

1. nitride semiconductor device, it is in the territory, n lateral areas with nitride multilayer thing semiconductor layer and has the nitride semiconductor device that has active layer between the territory, p lateral areas of nitride multilayer thing semiconductor layer, it is characterized in that:

At least one deck nitride semiconductor layer in territory, said n lateral areas, be first nitride semiconductor film that will contain In and have the n side stratified film that is laminated with second nitride semiconductor film of the different compositions of this first nitride semiconductor film, and the thickness of at least one side in above-mentioned first nitride semiconductor film or above-mentioned second nitride semiconductor film is

Or below;

At least one deck nitride semiconductor layer in territory, above-mentioned p lateral areas, be the 3rd nitride semiconductor film that will contain Al and have and the stacked p side stratified film that forms of the tetrazotization thing semiconductor film of the different compositions of the 3rd nitride semiconductor film, and the thickness of at least one side in above-mentioned the 3rd nitride semiconductor film and the above-mentioned tetrazotization thing semiconductor film is Or below;

Said n side stratified film and above-mentioned p side stratified film, the number of plies and/or composition are different mutually.

2. nitride semiconductor device as claimed in claim 1 is characterized in that, above-mentioned first nitride semiconductor film is by In _xGa _1-xN forms, 0＜x＜1 wherein, and above-mentioned second nitride semiconductor film is by In _yGa _1-yN forms, wherein 0≤y＜1, y＜x.

3. nitride semiconductor device as claimed in claim 1 or 2, it is characterized in that, the thickness of at least one side in above-mentioned first nitride semiconductor film or above-mentioned second nitride semiconductor film is between the first adjoining nitride semiconductor film or different between the second adjoining nitride semiconductor film.

4. nitride semiconductor device as claimed in claim 1 or 2, it is characterized in that, consisting of of the III family element of at least one side in above-mentioned first nitride semiconductor film or above-mentioned second nitride semiconductor film, different at the composition of identical III family element between the first adjoining nitride semiconductor film or between the second adjoining nitride semiconductor film.

5. nitride semiconductor device as claimed in claim 1 or 2 is characterized in that said n side stratified film and active layer join and form.

6. nitride semiconductor device as claimed in claim 1 or 2 is characterized in that, above-mentioned first nitride semiconductor film and second nitride semiconductor film all are non-doping.

7. nitride semiconductor device as claimed in claim 1 or 2, it is characterized in that, among any one party of above-mentioned first nitride semiconductor film or second nitride semiconductor film, be doped with n type impurity, and the impurity concentration of above-mentioned first nitride semiconductor film is different with the impurity concentration of above-mentioned second nitride semiconductor film.

8. nitride semiconductor device as claimed in claim 1 or 2, it is characterized in that, among above-mentioned first nitride semiconductor film and second nitride semiconductor film, all be doped with n type impurity, and the impurity concentration of above-mentioned first nitride semiconductor film is different with the impurity concentration of above-mentioned second nitride semiconductor film.

9. nitride semiconductor device as claimed in claim 1 or 2 is characterized in that, above-mentioned the 3rd nitride semiconductor film is by Al _aGa _1-aN forms, 0＜a≤1 wherein, and above-mentioned tetrazotization thing semiconductor film is by In _bGa _1-bN forms, wherein 0≤b＜1, b＜a.

10. nitride semiconductor device as claimed in claim 9, it is characterized in that, the thickness of at least one side in above-mentioned the 3rd nitride semiconductor film or the above-mentioned tetrazotization thing semiconductor film is between the 3rd adjoining nitride semiconductor film or different between the adjoining tetrazotization thing semiconductor film.

11. nitride semiconductor device as claimed in claim 9 is characterized in that, above-mentioned p side stratified film and active layer join and form.

12. nitride semiconductor device as claimed in claim 1 or 2 is characterized in that, above-mentioned the 3rd nitride semiconductor film and tetrazotization thing semiconductor film all are non-doping.

13. nitride semiconductor device as claimed in claim 1 or 2, it is characterized in that, be doped with p type impurity among any one party in above-mentioned the 3rd nitride semiconductor film or tetrazotization thing semiconductor film, the impurity concentration of above-mentioned the 3rd nitride semiconductor film is different with the impurity concentration of above-mentioned tetrazotization thing semiconductor film.

14. nitride semiconductor device as claimed in claim 1 or 2, it is characterized in that, all be doped with p type impurity at above-mentioned the 3rd nitride semiconductor film and tetrazotization thing semiconductor film among the two, the impurity concentration of above-mentioned the 3rd nitride semiconductor film is different with the impurity concentration of above-mentioned tetrazotization thing semiconductor film.