More specifically, gallium nitride semiconductor layers may be fabricated by etching an underlying gallium nitride layer on a sapphire substrate, to define at least one post in the underlying gallium nitride layer and at least one trench in the underlying gallium nitride layer. The at least one post...http://www.google.de/patents/US6521514?utm_source=gb-gplus-sharePatent US6521514 - Pendeoepitaxial methods of fabricating gallium nitride semiconductor layers on sapphire substrates
