4.5 kV MCT with buffer layer and anode short structure

Abstract

MOS controlled thyristors (MCTs) with 4.5 kV static blocking voltage have been fabricated and characterized. A buffer layer with anode shorts has been adapted to the conventional MCT structure to reach the high blocking voltage together with a low on-state voltage. Three different cathode designs with varying emitter area, turn-on channel width and turn-off channel width, have been realized. These IMCTs show MOS controlled turn-on at anode voltages as low as 2.2 V. The on-state voltage is 1.6 V at 100 A cm/sup -2/. The leakage current of these devices is less than 2/spl middot/10/sup -5/ A cm/sup -2/ at room temperature and 4.5 kV blocking voltage. It was demonstrated that these MCTs are able to turn off a current density of 50 A cm/sup -2/ at a line voltage of 3.5 kV in 10 /spl mu/s under inductive load without any snubber, thereby producing a turn-off energy density of approximately 0.7 Jcm/sup -2/.