Semiconductor device

A semiconductor device comprising:

• a substrate;
• a first nitride semiconductor layer provided on the substrate;
• a second nitride semiconductor layer provided on the first nitride semiconductor layer;
• a first electrode provided above a lower surface of the first nitride semiconductor layer and serving as a source electrode or an anode electrode;
• a second electrode provided above the lower surface of the first semiconductor layer and serving as a drain electrode or a cathode electrode;
• an electrode portion provided above a lower surface of the second nitride semiconductor layer;
• and
• an interlayer insulating film covering the second electrode, wherein:
• the interlayer insulating film partially has an opening and a second electrode wiring connected to the second electrode is provided in the opening,
• the first nitride semiconductor layer has a two-dimensional electron gas channel in a vicinity of an interface with the second nitride semiconductor layer,
• the first nitride semiconductor layer and the second nitride semiconductor layer form a semiconductor layer stacked body,
• the electrode portion is disposed between the first electrode and the second electrode, in plan view,
• an interface between the electrode portion and the second nitride semiconductor layer has an energy barrier indicating a rectifying function in a forward direction from the electrode portion to the second nitride semiconductor layer,
• a bandgap of the second nitride semiconductor layer is wider than a bandgap of the first nitride semiconductor layer,
• the electrode portion has a potential substantially equal to a potential of the second electrode,
• the two-dimensional electron gas channel under the electrode portion is in a conductive state between the first electrode and the second electrode, when a maximum operating voltage, which renders the first electrode positive with respect to the second electrode, is applied between the first electrode and the second electrode,
• a side surface and an upper surface of the electrode portion are in contact with the second electrode, and
• a first contact surface, in which the side surface of the electrode portion contacts to the second electrode, and a second contact surface, in which the upper surface of the electrode portion contacts to the second electrode, are continuous.