| 摘要 |
PURPOSE:To increase an emitter injection efficiency of a current amplification factor by providing a P type amorphous silicon layer including B and Ge on an N type layer of a P type silicon substrate. CONSTITUTION:An amorphous silicon layer 8 containing B and Ge is deposited on an N layer 3 of a P silicon substrate 1 by laying SiH4 in the atmosphere of B and Ge. The maximum concentration of P impurity B which can be included in the amorsphous silicon layer 8 is controlled by solid solubility, limit depends on an amount of distortion created with introduction of other elements. This limit is loosened by introduction of Ge which has a larger ion radius than that of Si, and the maximum concentration of B is largely increased. Further, a hetero junction is formed between layers 3 and 4, so a potential barrier against electrons is higher than a barrier against positive holes. Therefore, an emitter injection efficiency or a current amplification factor is much more increased. Since Ge is inactive, the property of the layer 8 is not deteriorated. |
