| 摘要 |
PURPOSE:To improve noise characteristics by forming a second optical absorption layer, which contains an impurity in high concentration, has thickness capable of sufficiently absorbing light except aimed light and does not aim at photodetection, besides an optical absorption layer for detecting rays. CONSTITUTION:A first optical absorption layer 16 absorbing and detecting first light is formed on a semiconductor substrate 10, and a second optical absorption layer 12 preventing projection to the first optical absorption layer 16 of second light projected into the substrate 10 is shaped. An N type InP buffer layer 11, the S doped N type InGaAs layer 12 as the second optical absorption layer, an S doped N type InP layer 13, a non-doped N type InGaAs layer 14 and a non- doped N type InP layer 15 are crystal-grown on a substrate such as an S doped or Sn doped N type InP substrate 10 in succession. Zn is diffused or Cd is diffused to the non-doped N type InP layer 15 to form the P type InP layer 16 as the first optical absorption layer. P type electrodes 17 are attached to the surface of the P type InP layer 16 and an N type electrode 18 is attached to the lower surface of the N type InP substrate 10 respectively and formed to a mesa shape through etching, and antireflection coating 19 is attached to the surface, thus forming a light-receiving element. |
