ABSTRACT
Power semiconductor devices are the most important functional elements in all power conversion applications. The most notable power devices are gate turn-off thyristors, power bipolar junction transistors, power metal–oxide–semiconductor field-effect transistors (MOSFET), insulated-gate bipolar transistors, and integrated gate-commutated thyristors. The thyristor, also called a silicon-controlled rectifier, is basically a four-layer three-junction pnpn device. The device is turned on by applying a short pulse across the gate and cathode. Once the device turns on, the gate loses its control to turn off the device. A semiconductor device is categorized as a bipolar type when its conduction current is made of both electron and hole currents. A thyristor is a bipolar type power semiconductor device with a very high level of conductivity modulation. The application of a negative voltage to the gate during turn-off helps to evacuate stored charge in the device and aids the recovery mechanisms. The need to ruggedize power MOSFETs is related to device reliability.
