Patent ID: 8735938

Claim:
A semiconductor device comprising a buffer and a functional laminate including a plurality of nitride semiconductor layers, on a substrate, wherein the functional laminate includes a first n-type or i-type Al x Ga 1-x N layer (0≦x<1) on the buffer side, and an Al z Ga 1-z N adjustment layer containing p-type impurity, which has an approximately equal Al composition to the first Al x Ga 1-x N layer (x−0.05≦z≦x+0.05, 0≦z<1) is provided between the buffer and the functional laminate, wherein the buffer includes an Al α Ga 1-α N layer (0<α≦1) at an outmost portion of the buffer on the functional laminate side, and difference between an Al composition α of the Al α Ga 1-α N layer and an Al composition x of the first Al x Ga 1-x N layer is 0.1 or more.