| 摘要 |
PURPOSE:To increase the current amplification factor, simultaneously with making the withstand voltage and gain-bandwidth product (fT) higher, by providing an N-type semiconductor layer whose impurity density is higher than another N-type semiconductor layer of a high impurity density, and which has a junction with a P-type semiconductor layer for an emitter, at a different position from that of the junction of the N-type semiconductor layer of the high impurity density with the P-type layer. CONSTITUTION:A basis 21 comprises a P-type silicon substrate 21a and an N-type epitaxial semiconductor layer 21b provided on this substrate 21a. And, a P-type semiconductor layer 23 for an emitter, and a P-type semiconductor layer 25 for a collector at a domain a specified distance apart from the semiconductor layer 23, are provided on this basis 21. Besides, an N-type semiconductor layer 31 whose impurity density is higher than that of another N-type semiconductor layer 27, and which has a junction with a P-type semiconductor layer for an emitter at a different position from that of the N-type semiconductor layer 27 of the high impurity density, in this case at the bottom of the P-type semiconductor layer 23 for the emitter, is provided on the basis 21. As the injection efficiency of minority carriers lowers at the bottom section of the P-type semiconductor layer 23 for the emitter with constitution like this, the sneaking-in current to the substrate decreases. This enables making the withstand voltage and fT higher, and increases the current amplification factor. |
