| 摘要 |
PURPOSE:To improve the high speed of a hetero junction semiconductor device by forming a collector layer of a non-doped compound semiconductor, implanting an impurity only to a region necessary to operate a transistor to be conductive, thereby suppressing the area of the collector layer to the necessary minimum limit to reduce a junction capacity between a base and the collector. CONSTITUTION:An impurity-containing compound semiconductor base layer such as an N<+> type GaAs base layer 5 is formed on a non-doped compound semiconductor collector layer such as an I-type GaAs collector layer 3, an impurity is then selectively implanted from the front surface, and the step of conducting a region necessary to operate a transistor in the non-doped compound semiconductor collector layer such as an N-type GaAs base region 3A is contained. Thus, since the impurity is implanted only to the region necessary to operate the transistor in the collector layer and the others are non-doped, a junction capacity between the base and the collector is reduced to improve the high speed thereof.
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