Switching device

A switching device comprising:

• a switching element that has a semiconductor substrate, a first electrode and a second electrode disposed on one surface of the semiconductor substrate, and a gate unit disposed between the first electrode and the second electrode on the one surface, and that makes a portion between the first electrode and the second electrode conductive by forming a channel region on the semiconductor substrate when a gate voltage exceeding a predetermined threshold voltage is applied to the gate unit;
• and
• a drive circuit that switches between ON and OFF of the switching element by applying the gate voltage to the gate unit of the switching element, wherein
• the semiconductor substrate includes a semiconductor-stacked body formed by having a first semiconductor layer and a second semiconductor layer stacked, has a hetero-junction interface at a junction portion between the first semiconductor layer and the second semiconductor layer, and uses a 2-dimensional electron gas layer generated in the hetero-junction interface as the channel region,
• the switching element has a field application electrode that is connected to the semiconductor substrate with an insulating film interposed therebetween, and
• the drive circuit has a field control unit that applies an electric field to the hetero-junction interface from the field application electrode by applying a bias voltage to the field application electrode.