The Insulated Gate Bipolar Transistor is a fusion of a MOSFET and BJT into one device. This is achieved by adding a layer of P type silicon to the MOSFET between the drain and the metal contact for the drain. This combines with the N silicon of the drain and the P layer of the body to make a PNP transistor where the new P layer is the emitter, the drain is the base, and the body is the collector. Since the body is shorted to the source in a MOSFET the collector of the PNP transistor is also shorted to the source of the MOSFET. This makes the PNP and MOSFET form the configuration shown in this circuit. The IGBT is notable for being able to handle very high voltages and currents in one device, although not both at once of course or else it’ll melt almost instantly from the many thousands of watts of heat dissipation that would create. In fact, of all the transistor types, the IGBT is the one that is best at being able to handle both very high currents and very high voltages.
