Patent ID: 7402843

Claim:
A group III-V compound semiconductor device, comprising: a first semiconductor layer made of Al a Ga b In 1-a-b P (where 0≦a≦1, 0≦b≦1, 0≦a+b≦1); a second semiconductor layer made of Al x Ga y In 1-x-y P (where 0≦x≦1, 0≦y≦1, 0≦x+y≦1) formed on the first semiconductor layer; and a third semiconductor layer made of Al c Ga 1-c As (where 0≦c≦1) formed in contact with the second semiconductor layer, wherein a Ga content y in the second semiconductor layer is smaller than a Ga content b in the first semiconductor layer, the second semiconductor layer is provided between the first semiconductor layer and the third semiconductor layer, and the Ga content y is less than 0.15.