Patent ID: 8586994

Claim:
A semiconductor device, comprising: an electron transit layer made of a semiconductor disposed on a substrate, the electron transit layer having a first band gap; an electron supply layer disposed on the electron transit layer, the electron supply layer being made of a semiconductor having a second band gap that is wider than the first band gap; a barrier-forming layer disposed on the electron supply layer, the barrier-forming layer being made of a semiconductor having a third band gap that is narrower than the second band gap; an upper channel layer disposed on the barrier-forming layer, the upper channel layer being made of a semiconductor doped with an impurity; a side surface of the barrier-forming layer and the upper channel layer formed by partly removing the barrier-forming layer and the upper channel layer; an insulating film disposed on the side surface; a gate electrode disposed on the insulating film; a source electrode connected to the upper channel layer; and a drain electrode connected to the electron supply layer or the electron transit layer.