Semiconductor device and manufacturing method for the same

A semiconductor device, comprising:

• a first GaN based semiconductor layer;
• a second GaN based semiconductor layer disposed on the first GaN based semiconductor layer, the second GaN based semiconductor layer having a bandgap larger than a bandgap of the first GaN based semiconductor layer;
• a source electrode disposed on the second GaN based semiconductor layer, the second GaN based semiconductor layer having a first film thickness between the source electrode and the first GaN based semiconductor;
• a drain electrode disposed on the second GaN based semiconductor layer;
• a gate electrode disposed between the source electrode and the drain electrode, a gate insulating film being disposed between the gate electrode and the first GaN based semiconductor layer, a part of the gate insulating film being in contact with the first GaN based semiconductor layer, the gate insulating film being separated from the drain electrode, the second GaN based semiconductor layer having a second film thickness between the gate electrode and the first GaN based semiconductor layer, the second film thickness being thinner than the first film thickness;
• a p-type third GaN based semiconductor layer disposed between the second GaN based semiconductor layer and an end portion on the drain electrode side of the gate electrode, the gate insulating film being disposed between the gate electrode and the third GaN based semiconductor layer, the third GaN based semiconductor layer disposed on the second GaN based semiconductor layer, p-type impurity concentration of the p-type third GaN based semiconductor layer being 1×1017 cm−3 or more and 1×1019 cm−3 or less, film thickness of the p-type third GaN based semiconductor layer being 10 nm or more and 100nm or less;
• an insulating film disposed on the third GaN based semiconductor layer on an opposite side of the second GaN based semiconductor layer;
• and
• a first field plate electrode, the insulating film being disposed between the first field plate electrode and the third GaN based semiconductor layer,
• wherein the third GaN based semiconductor layer is located between the second GaN based semiconductor layer and an end portion on the drain electrode side of the first field plate electrode.