Semiconductor GTO switching device with radially elongated cathode emitter regions of increasing length

摘要

A gate turn-off thyristor in which a cathode-emitter layer is divided into a plurality of strip-like regions which are radially arrayed on a major surface of a semiconductor substrate in a coaxial multi-ring pattern including a plurality of coaxially arrayed rings. The cathode-emitter strips belonging to a given one of the rings have some radial length. The cathode-emitter strips belonging to the inner ring of a coaxial multi-ring pattern have a smaller radial length than that of the cathode-emitter strips constituting the outer ring. A cathode electrode is contacted to the cathode-emitter strip in low resistance ohmic contact. A gate electrode is ohmic contacted with a low resistance to a cathode-base layer located adjacent to the cathode-emitter strip so as to enclose it. An anode electrode is ohmic contacted with a low resistance to the anode-emitter layer. With the structure of GTO, turn-off operation of unit GTO's each including a cathode-emitter strip is equalized.