Patent ID: 7304330

Claim:
A nitride semiconductor device, which comprises a III-V Group nitride semiconductor layer being composed of a III Group element consisting of at least one of a group containing of gallium, aluminum, boron and indium and V Group element consisting of at least nitrogen among a group consisting of nitrogen, phosphorus and arsenic, comprising: a first nitride semiconductor layer comprising said III-V Group nitride semiconductor layer of n-type aluminum gallium nitride as a charge supply layer being deposited on a substrate; a second nitride semiconductor layer comprising said III-V Group nitride semiconductor layer of non-doped gallium nitride being deposited on said first nitride semiconductor and not containing aluminum; a third nitride semiconductor layer of non-doped gallium nitride as a channel layer formed between said substrate and said first nitride semiconductor layer; and a control electrode making Schottky contact with said second nitride semiconductor layer; wherein said second nitride semiconductor layer comprises a film having a crystallinity with minute grains, and whose film forming temperature is lower than said first nitride semiconductor layer for causing crystallinity with minute grains.