| 摘要 |
PURPOSE:To increase dv/dt tolerate amount without lowering sensitivity by extracting a displacement current from the short circuit electrode provided in the inside of an emitter wherein the displacement current is generated in the concave type light sensing region of a photofiring SCR and other places except a band type n-emitter layer protruded into the region. CONSTITUTION:The band part 4 of an n-type emitter layer protrudes into the concave part 5 which reaches around the space charge region of a p-base layer 3 from the surface, wherein the space charge region is generated at the time of reverse bias. And a light sensing part 5 exists at the top part of the layer 3. The concave part 5 held by the band part 41 provides narrow grooves 52. The outside of the region 31 exists no n-emitter and the p-base layer 3 reaches the surface and the region 31 shorts to a cathode electrode 7 together with the emitter layer. In this composition, the displacement current caused under the narrow grooves 52 is small and the displacement current caused by dv/dt at the region of the outside of the narrow grooves is extracted from the electrode 7 and will not flow into the band part 41. Therefore, dv/dt tolerate amount will be improved. The light at the sides of the region has nothing to do with firing, so firing sensitivity will little lower even if the area of the concave part 5 is reduced. |
