Patent ID: 7132699

Claim:
A compound semiconductor device comprising: a substrate; a channel layer disposed above said substrate and consisting essentially of GaN; an electron supply layer disposed above said channel layer and consisting essentially of n-type Al.sub.qGa.sub.1−qN (0<q≦1); a cap layer disposed above said electron supply layer, having a surface, and consisting essentially of n-type GaN; a gate electrode disposed on the surface of said cap layer and forming a Schottky contact; recesses formed on both sides of said gate electrode on source and drain sides by removing at least part of said cap layer from the surface, said recess having a bottom surface of a roughness larger than a roughness of the surface of said cap layer under said gate electrode; a source electrode disposed on the bottom surface of said recess on the source side; and a drain electrode disposed on the bottom surface of said recess on the drain side.