The field assisted turn-off thyristor: A regenerative device with voltage controlled turn-off

A regenerative device with voltage controlled turn-off, the field assisted turn-off (FATO) thyristor, is described. This shorted-cathode device incorporates an MOS gate fabricated along the sidewall of a plasma-etched trench. When the thyristor is in the on state and a negative voltage is applied to this gate, holes are pulled from the electron-hole plasma towards the sidewall, travel up the sidewall and are collected by a P⁺region shorted to the cathode. To maintain charge neutrality, then, the N⁺cathode stops injecting electrons and the device comes out of regeneration. In this manner, the devices thus far fabricated can turn off a current density of 8 A/cm²in excess of the holding current. By ramping the voltage on the off gate more rapidly, a current density of 40 A/cm²in excess of the holding current can be turned off, with a displacement current through the off gate of 1/20 of the anode current in excess of the holding current.