Patent ID: 8664696

Claim:
A nitride semiconductor device comprising: a first semiconductor layer made of a nitride semiconductor of a first conductivity type, provided on a substrate; a second semiconductor layer made of a nitride semiconductor of a second conductivity type, provided on the first semiconductor layer and having a sheet carrier concentration being same as a sheet carrier concentration of the first semiconductor layer; a third semiconductor layer made of a nitride semiconductor with a forbidden band width wider than a forbidden band width of the second semiconductor layer, provided on the second semiconductor layer; a first main electrode electrically connected with the second semiconductor layer; a second main electrode provided at a distance from the first main electrode and electrically connected with the second semiconductor layer; and a control electrode provided within a first trench via an insulating film, the first trench being disposed between the first main electrode and the second main electrode, penetrating the third semiconductor layer and the second semiconductor layer, and extending into the first semiconductor layer.