Patent ID: 8207556

Claim:
A group III nitride semiconductor device, comprising: a group III nitride semiconductor supporting base, the group III nitride semiconductor supporting base being composed of a group III nitride semiconductor, the group III nitride semiconductor supporting base having a primary surface, the primary surface being tilted at an angle with reference to a reference plane, the reference plane being orthogonal to a reference axis, and the reference axis extending in a direction of a c-axis of the group III nitride semiconductor; a gallium nitride based semiconductor region provided in contact with the primary surface of the group III nitride semiconductor supporting base, the gallium nitride based semiconductor region having an oxygen, the primary surface having one of semi-polarity and non-polarity, the gallium nitride based semiconductor region including a first conductive type gallium nitride based semiconductor layer and one or more gallium nitride based semiconductor layers, a thickness of the first conductive type gallium nitride based semiconductor layer being larger than that of any of the gallium nitride based semiconductor layers, the first conductive type gallium nitride based semiconductor layer including a donor, and the donor being different from oxygen; and an active layer provided in contact with the gallium nitride based semiconductor region.