Semiconductor device

A semiconductor device, comprising:

• a substrate;
• a semiconductor layer stacked body including a first nitride semiconductor layer above the substrate and a second nitride semiconductor layer which is on the first nitride semiconductor layer and has a band gap wider than a band gap of the first nitride semiconductor layer;
• a gate electrode on the semiconductor layer stacked body;
• a source electrode and a drain electrode located on opposite sides of the gate electrode and spaced apart from the gate electrode in a plan view of the semiconductor layer stacked body;
• a first active region which has a first carrier layer located in the first nitride semiconductor layer, the source electrode, the drain electrode and the gate electrode being disposed in the first active region in the plan view;
• a second active region which is on an extension of a long side of the drain electrode in the plan view, and has a second carrier layer located in the first nitride semiconductor layer, the second carrier layer being separated from the first carrier layer by an element isolation region containing no carrier;
• a gate extraction electrode located opposite a short side of the drain electrode and disposed in the second active region in the plan view, and electrically connected with the gate electrode;
• and
• a source extraction electrode directly on the semiconductor layer stacked body and disposed in the second active region in the plan view and electrically connected with the source electrode.