Semiconductor gate turn-off device

Claim 1

A gate turn-off device comprising: a semiconductor body including at least six layers of alternating first and second conductivity types of semiconductor material to form a plurality of interior rectifying junctions, a first exterior layer of said body formed from a first conductivity type material more heavily doped than the remaining layers of said first conductivity type in order to provide a low resistivity emitter, said first exterior layer covering only a portion of the exterior surface of said body and disposed in contact with a first intermediate layer of said second conductivity type material having a portion extending to the remaining portion of the exterior surface of said body, a second exterior layer of said body formed from said second conductivity type material having a high doping level in contact with a second intermediate layer of said second conductivity type material having a lower doping level, a gate electrode formed in contact with said first intermediate layer, a second electrode formed in contact with said first exterior layer, and a third electrode formed in contact with said second exterior layer, said device operable to be biased into a regenerative process to transition said interior rectifying junctions from blocking conditions into avalanche conditions, means for applying a gating signal to said gate electrode to provide fast turn-off characteristics by terminating said regenerative process, the termination of said regenerative process being facilitated by the effective removal of said first exterior layer emitter during turn-off due to the low resistivity of said emitter which causes reverse current to be injected into said first intermediate layer during switching.