Patent ID: 8164115

Claim:
A nitride semiconductor device comprising: a substrate; a first nitride semiconductor layer formed over the substrate; a second nitride semiconductor layer formed on the first nitride semiconductor layer and having a larger band gap energy than the first nitride semiconductor layer; a third nitride semiconductor layer formed on the second nitride semiconductor layer and including a p-type nitride semiconductor with at least a single-layer structure; a gate electrode formed on the third nitride semiconductor layer; and a source electrode and a drain electrode formed in regions located on both sides of the gate electrode, respectively, wherein the third nitride semiconductor layer has a thickness greater in a portion below the gate electrode than in a portion below the side of the gate electrode, wherein the third nitride semiconductor layer includes a first p-type layer and a second p-type layer sequentially formed in this order from the substrate side, and the first p-type layer has a thickness greater in the portion below the gate electrode than in portions located between the source electrode and the gate electrode and between the drain electrode and the gate electrode.