Systems and methods are provided for nonvolatile memory devices that incorporate a band-gap engineered gate stack with asymmetric tunnel barriers. One embodiment of a memory device includes first and second source/drain regions separated by a channel region in a substrate, a control gate, and a gate...http://www.google.de/patents/US6950340?utm_source=gb-gplus-sharePatent US6950340 - Asymmetric band-gap engineered nonvolatile memory device
