Patent ID: 8183597

Claim:
A GaN semiconductor device, wherein comprising: a III-V nitride semiconductor layer including a first layer of first III-V nitride semiconductor having a first bandgap energy, and a second layer of second III-V nitride semiconductor having a second bandgap energy larger than the first bandgap energy, the second layer having a first width; a composite anode electrode including a first anode electrode formed on a surface of the III-V nitride semiconductor layer and in Schottky contact with the III-V nitride semiconductor layer with a first Schottky barrier, the first anode electrode having a second width narrower than the first width, and a second anode electrode wider than the first anode electrode, covering the first anode electrode and in electrical contact with the first anode electrode, both sides of the second anode electrode being formed on the surface of the III-V nitride semiconductor layer and in Schottky contact with the III-V nitride semiconductor layer with a second Schottky barrier, the second Schottky barrier being higher than the first Schottky barrier; a contact layer formed on a side of the III-V nitride semiconductor layer; a cathode electrode formed on a surface of the contact layer and in ohmic contact with the contact layer; and an insulating protection film formed on the surface of the III-V nitride semiconductor layer between the second anode electrode and the cathode electrode, wherein the insulating protection film has a first end portion sandwiched, in a thickness direction of the device, between the second anode electrode and the III-V nitride semiconductor layer and a second end portion sandwiched, in the thickness direction of the device, between the cathode electrode and the contact layer.