Patent ID: 8344422

Claim:
A semiconductor device, comprising: a lower barrier layer composed of a layer of AlxGa1-xN (0≦x≦1) in a state of strain relaxation; and a channel layer composed of a layer of InyGa1-yN (0≦y≦1) disposed on said lower barrier layer, said channel layer having band gap that is smaller than band gap of said lower barrier layer and exhibiting compressive strain, wherein a gate electrode is formed over said channel layer via an insulating film, and a source electrode and a drain electrode serving as ohmic electrodes are formed over said channel layer, wherein said insulating film is polycrystalline or amorphous, and wherein said insulating film covers over entire region of said channel layer sandwiched by said source electrode and said drain electrode, and circumference section of said insulation film covers sections of upper surfaces of said source electrode and said drain electrode.