| 摘要 |
PURPOSE:To obtain a photodiode which is of planar structure and easily formed in low capacity, in its turn, excellent in high-speed performance, by making at least one part of a second-conductivity type region, which is unconcerned with incidence of light, advance to a semiinsulating substrate. CONSTITUTION:First semiconductor layers 12 to 14 which show a first conductivity type are formed on one main surface of a semi-insulating substrate 10, and certain regions of the first semiconductor layers 12 to 14 are selectively converted into second-conductivity type regions 15 and 16 so as to form p-n junction. Signals of light made incident to this p-n junction are converted into electrical signals. In such a photodiode, at least one part of said second- conductivity type region 16, which is unconcerned with incidence of light, is made to advance to the semiinsulating substrate 10. For example, after the n<+>-InP layer 12, n-InGaAs layer 13, and n-InP layer 14 are formed on the iron- doped semiinsulating InP substrate 10, the Zn selective diffusion p<+> region 15 is formed so as to advance to the n<->-InGaAs layer 13. Further, the deep p<+> region 16 is formed so as to advance to the semi-insulating substrate 10.
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