| 摘要 |
PURPOSE:To obtain a photodiode characterized by excellent high speed property and no loss in photoelectric conversion efficiency, by reversing the conductivity of the specified third and second semiconductor layers, which are provided on the n-conductivity type first semiconductor layer, into a p-conductivity type, thereby forming a p-n junction. CONSTITUTION:On the n-conductivity type first semiconductor layer, the n- conductivity type second semiconductor layer, whose forbidden band width is narrower than that of the first semiconductor, is formed. The n-conductivity type third semiconductor layer, whose forbidden band width is larger than that of the second semiconductor layer, is provided. The conductivity of the third and second semiconductor layers is reversed into a p-type conductivity. Thus a p-n junction is formed. On an n<+> InP substrate 18, n<->-InP 11 is formed by, e.g., a vapor phase growing method. Then n<->-InGaAs 13 and then n-InP 14 are formed. Then, e.g., SiO2 insulating film 15 is formed on the surface of a wafer. Thereafter, one region is selectively removed by a photoresist proc ess. With the SiO2 film as a mask for impurity diffusion and with, e.g., Zn3P2, as a diffusion source, a (p) region 16, in which Zn is selectively diffused, is formed by heat treatment.
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