Patent ID: 7298123

Claim:
A power supply apparatus comprising: a field effect transistor (FET) that is disposed in a path of a main current that is a subject of power control, the FET including: a first gallium-nitride buffer layer, a first gallium-nitride layer formed on the first gallium-nitride buffer layer, a first n-type aluminum-gallium-nitride layer formed on the first gallium-nitride layer, and a control unit which conducts switching control on conduction of the main current flowing through said FET; and a diode that is disposed in the path of the main current that is switched on and off by the FET, the diode including a second gallium-nitride buffer layer, a second gallium-nitride layer formed on the second gallium-nitride buffer layer, and a second n-type aluminum-gallium-nitride layer formed on the second gallium-nitride layer.