Abstract: A thyristor having a collecting electrode which is formed on a specific base layer adjacent to a specific emitter layer of the thyristor in order to absorb an excessive current generated in the specific base layer. A plurality of pilot thyristors are arranged inside the collecting electrode. Each gate electrode of the pilot thyristors is connected to an emitter electrode of the thyristor of the immediately preceding stage. An emitter electrode of the final stage of the thyristors is used commonly with the collecting electrode. A turn-on current from the collecting electrode serves as a gate current of the main thyristor.

Abstract: A radiation-controllable thyristor is disclosed, which includes an electrical trigger main thyristor having four semiconductor layers each having mutually different conductivity types, and a plurality of stages of pilot thyristors commonly having three other layers excluding one emitter layer of the above main thyristor. First-stage one of the pilot thyristors is a light-triggering type thryistor having a photo-sensing area onto which a control radiation, such as light beam, is irradiated. A collector electrode is provided on another emitter layer of the main thryistor in such a way as to substantially surround the above pilot thyristors.

Abstract: A light-activated bi-directional thyristor of a planar structure having P type base layers for first and second thyristors in a light receiving section, the P type base layers being separated from each other by an N type base layer. An N type emitter layer is formed at that part of the P type base layer for the second thyristor which is located on the side of the light receiving section. A first auxiliary electrode is laminated to the N type emitter layer to form an amplifying gate section. A second auxiliary electrode is formed on the P type base layer which is located opposite the light receiving section. On-current of the amplifying gate section is supplied to a shorted emitter in the second thyristor, through a connector for electrically connecting the first and second auxiliary electrodes.

Abstract: A light-driven semiconductor device comprises an optical fiber having an output end located in the vicinity of a light sensitive area of a light trigger thyristor and a silicone rubber interposed between the output end of said light guide and the light sensitive area and pressed against said light sensitive area by said output end, whereby said output end is located relatively to said light sensitive area and a light signal emitted from said output end is led to said light sensitive area.