Gate turn-off thyristor

Claim 1

A gate turn-off thyristor comprising: a first emitter layer (31) of a first conductivity type; a first base layer (32) of a second conductivity type formed on said first emitter layer; a second base layer (33) of the first conductivity type formed on said first base layer; a second emitter layer (34) of the second conductivity type formed on said second base layer, said first emitter'layer consisting of high impurity concentration regions (38) and low impurity concentration regions (39), said second emitter layer being divided into a plurality of nearly rectangular emitter strips (34 1 to 34 n ) on said second base layer (33), and PN-junctions being formed between said emitter strips and said second base layer; an anode electrode (35) which is in contact with said first emitter layer; cathode electrodes (36 1 to 36 n ) which are in contact with said second emitter layer; and a gate electrode (37) which is in contact with said second base layer excluding said PN-junctions, characterized in that each of said high impurity concentration regions (38) of said first emitter layer (31) is formed to have a substantially uniform width and to surround at least part of the periphery of one of said low impurity concentration regions (39) having a nearly rectangular shape and formed within regions of said first emitter layer just below said emitter strips.