| 摘要 |
PURPOSE:To attain a high current-amplification factor, by forming a base electrode at a base portion positioning at the bottom of a concave which is approximately same or deeper in comparison with an emitter layer. CONSTITUTION:An N-layer is formed over an N<+> layer serving as a collector 3, a P-layer serving as a base is formed in the N type, and in the P-layer an N<+> layer serving as an emitter 1 is formed. In an NPN planer transistor formed in this way, a base electrode 5 is formed at the bottom of a concave 6 which is approximately same or deeper in comparison with the layer 1 and is formed in the P-layer 2 around the N<+> layer 1. By forming in this way, a current flowing from the base 2 is difficult to flow directly into the emitter and therefore it flows into just below the emitter 1. Accordingly, percentage of the current flowing from the collector 3 of the current flowing into the emitter 1 increases, resulting in a high current amplification factor. |
