Patent ID: 7015518

Claim:
A semiconductor device comprising: a substrate; a buffer layer over said substrate; a channel layer over said buffer layer, said buffer layer being between said channel layer and said substrate; a spacer layer over said channel layer, said channel layer being between said spacer layer and said buffer layer; an electron supplying layer over said spacer layer, said spacer layer being between said electron supplying layer and said channel layer, said electron supplying layer having a first conductivity impurity; a barrier layer over said electron supplying layer, said electron supplying layer being between said barrier layer and said spacer layer; an impurity diffusion layer in contact with said buffer layer, said channel layer, said spacer layer, electron supplying layer and said barrier layer, wherein said impurity diffusion layer includes a second conductivity impurity inverse in conductivity relative to said first conductivity impurity, wherein said first conductivity type impurity is a n-type and said second conductivity type impurity is an p-type, and wherein said substrate is a semi-insulating substrate (InP).