SEMICONDUCTOR DEVICE THAT CAN BE TURNED OFF

PROBLEM TO BE SOLVED: To prevent nonuniformities, that exists in a semiconductor element from becoming a high current density locally on turn-off by doping a second emitter region with an additional substance that operates as a doping substance in first conductive type at the upper side of the operating temperature of a semiconductor device. SOLUTION: When a GTO thyristor is turned on from a continuity state, a second emitter 4 is doped by an additional substance that operates as a first conductivity-type doping substance at the upper side of an operating temperature, namely 300 deg.C or higher, such as boron to avoid a current filament that is generated based on a second unavoidable non-uniformity. The additional substance performs a compensation operation, when a current filament is generated, thus reducing a transistor emitter efficiency at the part of an anode side consisting of regions 2 and 1 and 4 locally in the current filament. As a result, the turn-off current can be compensated totally.