| 摘要 |
PURPOSE:To prevent recombination of minority carrier of a base region and to improve a generating efficiency by holding a base region between a pair of layers each having high impurity concentration. CONSTITUTION:A P<+> type layer 7 having further high impurity concentration is provided at the surface side of a base region 1 made of P-type semiconductor, and the region 1 having lower concentration than those of FSF7 and BSF3 of P<+> type high concentration layers is held between the SFS7 and the BSF3 from the front and rear surfaces. For example, if the base 1 contains 1X10<17>cm<-3> of impurity concentration, the FSF1 and the BSF3 are set to 5X10<17>cm<-3> of impurity concentration. Thus, recombination of minority carrier in a boundary between the front and rear surfaces of the base region can be prevented by the BSF3 and the FSF7 having higher impurity concentration than that of the region 1, a collection efficiency in an emitter region 2 is improved, and a generating efficiency is improved. |
