Patent ID: 8772786

Claim:
A semiconductor structure, comprising: a substrate; a mesa structure disposed on a surface of the substrate, the mesa structure having slopped sidewalls oblique to the surface of the substrate, comprising: an electron donor layer disposed on, and along, the sloped sidewall of the mesa structure; a lower semiconductor layer having ends of an upper portion terminating at a lower portion of the electron donor layer; an upper semiconductor layer having ends terminating at an upper portion of the electron donor layer, having a different band gap from, and in direct contact with, the lower semiconductor layer; wherein a two-dimension electron gas region is formed having one portion disposed along a bottom portion of the upper semiconductor layer and another portion disposed along lower portions of the electron donor layer; an ohmic contact material disposed on the electron donor layer; wherein the upper semiconductor layer includes AlN; wherein the lower semiconductor layer is GaN; and wherein the electron donor layer is n-type doped AlGaN.