Controllable semiconductor rectifier

Claim 1

In a controllable semiconductor rectifier device including: a monocrystalline semiconductor body having planar major outer surfaces and four layer-type zones of alternatingly opposite conductivity types with the one of the inner zones of said semiconductor body which serves as the base zone, and which is adjacent to the one of the outer zones of said semiconductor body which serves as the emitter zone of the device, having a portion thereof which extends to the same one of said major outer surfaces of said semiconductor body as said emitter zone; a respective load current electrode ohmically contacting each of the two outer zones of said semiconductor body; and a control electrode ohmically contacting said portion of said base zone, the improvement wherein: said emitter zone has a first section with a substantial portion of its major outer surface being recessed from said one major outer surface of said semiconductor body, said first section extending to a first depth below said one major outer surface of said semiconductor body, and (b) a second section disposed at least at the edge of said first section of said emitter zone adjacent said control electrode, said second section lying along said one major outer surface of said semiconductor body and extending to a second depth from said one major outer surface of said semiconductor body which is less than said first depth; said respective load current electrode contacting said emitter zone only contacts the recessed portion of said major outer surface of said first section of said emitter zone; and said second section of said emitter zone and said base zone form a pn-junction having a major portion lying in a plane substantially parallel to said one major outer surface of the semiconductor body.