Abstract: A bidirectional photothyristor device comprises a semiconductive substrate including an NPNPN quintuple layer in which projections of both the outer layers Ns in the stacking direction are not overlapped so as to define two quadruple layer regions each having either one of the outer layers Ns as an end layer, a pair of main electrodes connecting the two quadruple layer regions in parallel relationship, a recess formed between the two quadruple layer regions within the semiconductive substrate and to which two intermediate P-N junctions are exposed, and means for applying a light trigger signal to the recess.

Abstract: By forming a metallic coating on a sufficiently cleaned semiconductor substrate through ion plating, a low power loss and high switching speed semiconductor device is obtained which differs from an ordinary semiconductor device with a diffused junction. In an interface between the metallic coating and the semiconductor substrate, a considerably thin metal-injected layer is formed toward the semiconductor substrate. Schottky barrier devices may be formed by the method of the invention.

Abstract: A light-activated semiconductor-controlled rectifier device comprising four layers of PNPN is disclosed in which a part of the edges of the PN junction formed between the intermediate P-type layer and the intermediate N-type layer is exposed on the same side on which the outer P-type layer is exposed, so that a photo-trigger signal is radiated on that exposed part of the edges of the PN junction.