| 摘要 |
A semiconductor substrate of the shape of a disc possesses a first main surface and a second main surface. The semiconductor substrate consists of an emitter layer on the side of the cathode, a second base layer, a first base layer, and an emitter layer on the side of the anode, which are laminated in the order mentioned from the side of the cathode toward the side of the anode. The circumference of the emitter layer on the anode side is short-circuited by an emitter short-circuiting layer on the anode side. On the second main surface is arrayed the emitter layer on the cathode side being divided into a plurality of strip units which are oriented in a radial manner from the center toward the periphery of the semiconductor substrate. The second base layer is exposed on the other portions on the second main surface. The emitter layers on the anode side are provided in the portions where the emitter layers on the cathode side are projected onto the anode side. The emitter short-circuiting layer on the anode side forms a plurality of fan-shaped portions which are oriented in a radial manner from the center toward the periphery of the semiconductor substrate so that the area per unit length in the radial direction of the emitter short-circuiting layer increases from the center toward the periphery. The emitter layers on the anode side and the emitter short-circuiting layers on the anode side are exposed to the first main surface, and are brought into contact with the anode electrodes. The emitter layers on the cathode side are in contact with the cathode electrodes, respectively. The second base layer is in contact with the control electrode, and a lead wire is connected to a central portion of the circular control electrode.
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