Patent ID: 7692298

Claim:
A semiconductor device comprising: a first semiconductor layer that is formed from a first semiconductor material; a second semiconductor layer that is formed from a second semiconductor material on the first semiconductor layer; a two-dimensional carrier that is formed within the first semiconductor layer and in the vicinity of an interface between the first semiconductor layer and the second semiconductor layer; a first concave portion that is formed penetrating at least the second semiconductor layer from a primary surface, which is a top surface, of the second semiconductor layer, and is formed from the interface to a predetermined depth in the first semiconductor layer; a first electrode that is formed on a bottom surface and side surface of the first concave portion and that forms a Schottky junction to the semiconductor layers which contact the bottom surface and the side surface of the first concave portion; and a second electrode that is formed in an area of the second semiconductor layer that is located away from the first electrode and that forms a low resistance contact with the second semiconductor layer, wherein: the primary surface of the second semiconductor layer faces the interface between the first semiconductor layer and the second semiconductor layer; the first semiconductor material and the second semiconductor material generate a piezoelectric polarization by distortion that is generated by the difference in the lattice constant between the first semiconductor layer and the second semiconductor layer; and the side surface of the first concave portion is inclined against the interface so that the inclination changes the thickness of the second semiconductor layer.