| 摘要 |
PURPOSE:To increase the current capacity of a GTO (gate turn-off thyristor) by providing a polycrystalline semiconductor layer (a resistance layer) on the first emitter region. CONSTITUTION:A polycrystalline semiconductor layer 21b is formed by a CVD method on the surface of the n<+> type layer 21c of a wafer diffused in n<+>21-p22-n<-> 23-p24 configuration, and an n<+> type layer 21a is further formed thereon so as to anable ohmic contact. When a polycrystalline semiconductor layer (a resistance layer) is consequently formed on the first emitter region 21, the anode currents of the respective GTO elements can be, when a plurality of GTO elements are operated in parallel, remarkably averaged, and the current capacity of the GTO can be accordingly increased. The current concentration at the turning off time is positively fed back, but since the current concentrated due to the existence of the resistance of an amitter region can be, when the current concentration occurs, dispersed, it displays the same effect as of introducing a negative feedback mechanism. |
