Patent ID: 8530937

Claim:
A compound semiconductor device comprising: a group-III nitride semiconductor layer in which a carrier supply layer and a carrier travel layer forming a hetero junction with the carrier supply layer are laminated; an insulation film located on the group-III nitride semiconductor layer; a drain electrode that includes a flange, which is located in a position which is a first distance away from an upper surface of the group-III nitride semiconductor layer in a film thickness direction across the insulation film and contacts the group-III nitride semiconductor layer in an opening portion provided in the insulation film; a source electrode that includes a flange, which is located in a position which is the first distance away from the upper surface of the group-III nitride semiconductor layer in the film thickness direction across the insulation film and contacts the group-III nitride semiconductor layer in an opening portion provided in the insulation film; a gate electrode located between the drain electrode and the source electrode; and a field plate electrode located between the drain electrode and the gate electrode at a position wherein a bottom surface of the field plate electrode is a second distance away from the upper surface of the group-III nitride semiconductor layer in the film thickness direction across the insulation film, the second distance being shorter than the first distance.