Patent ID: 7948011

Claim:
An enhancement mode high electron mobility transistor (HEMT) device comprised of aluminum gallium nitride (AlGaN) and gallium nitride (GaN) layers with an N-polar surface, comprising: (a) an epilayer structure comprising an AlGaN (1) layer on a GaN (1) layer, the GaN (1) layer on an AlGaN (2) layer, and the AlGaN (2) layer on a GaN (2) layer, wherein the AlGaN (1) layer, the GaN (1) layer, the AlGaN (2) layer, and the GaN (2) layer are in an N-face or (000-1) orientation; (b) a first region directly above the GaN (1) layer including a source; (c) a second region directly above the GaN (1) layer including the AlGaN (1) layer and a gate on the AlGaN (1) layer; (d) a third region directly above the GaN (1) layer including a drain, wherein the drain and the source are formed on the GaN (1) layer on opposite sides of the AlGaN (1) layer; (e) a fourth region directly above the GaN (1) layer and between the AlGaN (1) layer; the source, wherein the fourth region does not include the AlGaN(1) layer; (f) a fifth region directly above the GaN (1) layer and between the AlGaN (1) layer; and the drain, wherein the fifth region does not include the AlGaN (1) layer; and (g) a two dimensional electron gas (2DEG) channel at an interface between the AlGaN(2) layer and the GaN(1) layer, wherein the AlGaN (1) layer is thick enough such that polarization fields in the AlGaN (1) layer deplete the 2DEG channel under the AlGaN(1) layer at zero bias applied to the gate; (h) so as to form the enhancement mode HEMT.