Patent ID: 8530935

Claim:
A semiconductor device comprising: a substrate; a buffer layer arranged on the substrate; and a compound semiconductor layer which is arranged on the buffer layer and functions as a device region, wherein the buffer layer is configured by laminating two or more pairs of a first buffer and a second buffer, the first buffer is formed by laminating one or more pairs of a first nitride compound semiconductor layer and a second nitride compound semiconductor layer, the first nitride compound semiconductor layer having an aluminum composition therein, the second nitride compound semiconductor layer having a larger lattice constant than that of the first nitride compound semiconductor layer, the second buffer includes a third nitride compound semiconductor layer having a larger lattice constant than that of the first buffer, and a total Al composition of a pair of the first buffer and the second buffer on a compound semiconductor layer side is higher than that of a pair of the first buffer and the second buffer on a substrate side.