SEMICONDUCTOR DEVICE

PURPOSE:To obtain a semiconductor device having high cut-off capability, by providing a means for compressing a ring gate so that the conductive ring gate is uniformly contacted and compressed along the entire outer surface of a gate lead-out electrode. CONSTITUTION:A ring shaped groove part 100 is provided in a cathode electrode body10. A pair of belleville springs 300 are provided in the groove so that the surfaces face to each other through flat washers 200. Thus a conductive ring gate 600 is uniformly contacted and compressed along the entire outer surface of a gate lead-out electrode 60. Since metal such as silver and copper having a small electric resistance can be used for the ring gate 600, the resistance of wire can be made low even if the circumferential length of the gate lead-out electrode 60 is long aud a cut-off current becomes large. The voltage drop in the wire is almost negligible. Therefore, the applied voltage is intactly imparted to each segment without imparing cut-off capability.