Turn-on principles of MOS-GTO

Abstract

MOS-GTOs represent a new generation of turn-off thyristors offering considerable advantages in the turn-off behaviour as compared to conventional GTOs. However, MOS-GTOs generally require two control electrodes for turn-on, which might be regarded as a disadvantage. This paper shows that in MOS-GTOs with a p-channel cathode structure it is possible to turn the thyristor on and off by controlling only just one MOS gate electrode. As a triggering current for turn-on the MOS capacitance displacement current is used. MOS-GTOs with current gain βnpn = 30 and gate delay times of tgd = 8 µs were realized. Turn-on occurs homogeneously over the entire device. One-dimensional simulations indicate that thyristors with tgd = 1 µs can be realized, provided that βnpn 100.