| 摘要 |
PURPOSE:To increase photofiring sensitivity without increasing production processes by surrounding the end layer of one side of a four pnpn-layer by central pn- junction wherein the vicinity of the place exposed to the surface of a semiconductor is worked as a light sensing part. CONSTITUTION:An SCR in bevel structure is in forward blocking condition and a depletion layer 8 is formed at central pn-junction 3. In this condition, when light is applied to the vicinity of the exposed part 9 at the bevel part of the junction 3, the light is directly applied to the depletion layer 8 and carrier growth rate becomes good and firing sensitivity will be raised. A thin protective film is provided on the junction 3, but sensitivity will have little influence. The photofiring SCR by this composition has the most simple junction construction even if the SCR is bevel structure or planar type. No excess process is necessary in junction formation and firing sensitivity will be raised only by selecting the region of light radiation. |
