Patent ID: 8772785

Claim:
A semiconductor device comprising: semiconductor layers; an anode electrode; and a cathode electrode, wherein the semiconductor layers include a composition change layer, the anode electrode is electrically connected to one of principal surfaces of the composition change layer through a formation of a Schottky junction between the anode electrode and a part of the semiconductor layers, the cathode electrode is electrically connected to the other of the principal surfaces of the composition change layer through a formation of a junction between the cathode electrode and another part of the semiconductor layers, the anode electrode and the cathode electrode are capable of applying a voltage to the composition change layer in a direction perpendicular to the principal surface, and the composition change layer has composition that changes from a cathode electrode side toward an anode electrode side in the direction perpendicular to the principal surface of the composition change layer, has a negative polarization charge that is generated due to the composition that changes, and contains a donor impurity.