| 摘要 |
PURPOSE:To improve forward direction characteristics and to form a p-side electrode having a low contact resistance, in an InP/GaInAs P-I-N type photodiode, by removing a part of an InP window layer, partially exposing a GaInAs layer, and forming p-side contact from an Au/Pt/Ti electrode. CONSTITUTION:On an n<+> InP substrate 11, an N<-> InP layer 12 (buffer layer), an n<-> GaInAs layer 13 and an n InP layer 14 are sequentially formed by epitaxial growth. Then, an SiNx film 16 is formed on the surface. A window is provided in the SiNx film 16. Zn or Cd is diffused from the surface and a p<+> layer 15 is formed. In this diffusion of ptype impurities, a p-n junction plane is formed in the GaInAs layer 13. Then, a groove 23 is formed in the electrode forming part of the nInP layer 14 until the GaInAs layer is exposed by chemical etching. An Au/Pt/Ti electrode 20 is formed at the part of the groove 23. Then, the SiNx film 16 is attached. Thereafter, the p<+> layer 15 is formed by the diffusion of Zn. In this method, since the diffusion is carried out directly in the surface of the GaInAs, the surface concentration becomes high further-more, and excellent contact can be obtained. |
