Patent ID: 7495268

Claim:
A semiconductor device comprising: a semiconductor substrate; a channel layer formed on said semiconductor substrate; a donor layer formed on said channel layer; a first Schottky layer formed on said donor layer; a second Schottky layer formed on said first Schottky layer; a first gate electrode formed on said first Schottky layer, said first gate electrode forming a Schottky barrier junction with said first Schottky layer; a first source electrode and a first drain electrode which are formed so as to sandwich said first gate electrode, and are electrically connected to said channel layer; a second gate electrode which is: formed on said second Schottky layer; forming a Schottky barrier junction with said second Schottky layer; and made of a material different from said first gate electrode; and a second source electrode and a second drain electrode which are formed so as to sandwich said second gate electrode, and are electrically connected to said channel layer.