Patent ID: 6919589

Claim:
A semiconductor device comprising: a GaAs substrate; a buffer layer provided on the GaAs substrate, the buffer layer being made of a semiconductor, and at least a part of the semiconductor having a lattice constant larger than a lattice constant of GaAs; a channel layer provided on the buffer layer, and being made of In u1 Ga 1−u1 As; an electron supply layer provided on or under the channel layer, and being made of n-type In v1 Al 1−v As; a Schottky contact layer provided on the channel layer and the electron supply layer, at least a part of the Schottky contact layer being made of non-doped In y2 Al 1−y2 As; a n-type In x (Ga 1−y Al y ) 1−x P layer provided on the Schottky contact layer; a n-type In u2 Ga 1−u2 As ohmic contact layer provided on the n-type In x (Ga 1−y Al y ) 1−x P layer; a gate electrode provided on the Schottky contact layer; and a source electrode and a drain electrode provided on the ohmic contact layer, wherein the Schottky contact layer has a non-doped InAlAs layer and an AlGaAs layer provided thereon.