Patent ID: 7745851

Claim:
A high electron mobility device comprising: a substrate of semiconductor material; a first layer of a first polytype of the semiconductor material on the substrate, the first layer being an off-axis layer and having a narrow mesa region that extends from a first main surface of the first layer; a regrown layer of the first polytype over the narrow mesa region, the regrown layer having an on-axis surface over a top surface of the narrow mesa region; a source region in the regrown layer over a first sidewall of the narrow mesa region; a drain region in the regrown layer over a second sidewall of the narrow mesa region; and a second layer of a second polytype of the semiconductor material on the regrown layer, wherein a hetero-interface is formed between the regrown layer and the second layer over the top surface of the narrow mesa region, wherein the second layer over the top surface of the narrow mesa region is substantially a single crystal domain of the second polytype.