| 摘要 |
PURPOSE:To reduce dark current, by a method wherein a first recess is provided in an InO substrate and filled with either an InP or InxGa1-xAs1-yPy layer of a first conductivity type, and a second recess is provided in this layer and filled with eigher an InGaAs or Inx'Ga1-x'As1-y'Py' (y'<y) layer of the same conductivity type as the former layer, which is then protected by a layer of the conductivity type opposite to the first conductivity type. CONSTITUTION:A first recess 11 is formed in the surface of a semi-insulative InP substrate 10 and filled with either an N<-> type InP or InxGa1-xAs1-yPy epitaxial layer 12 having an impurity concentration of 5X10<15>/cm<3>. A second recess 13 is formed in a predetermined region in the layer 12 and filled with either an InGaAs or Inx'Ga1-x'As1-y'Py', epitaxial layer 14 having an impurity concentration of 5-10<15>/cm<3>. The relationship between y and y' is particularly specified to be y'<y. A P<+> type InGaAs protection layer 15 is formed on the surface of the layer 14, together with a P<+> type InP protection layer 16 which is connected to the layer 15 and which extends over a part of the surface of the layer 12, by diffusion or ion implantation. In this way, a photodiode having reduced surface leakage current is obtained. |
