| 摘要 |
PURPOSE:To improve the breakdown strength, by forming an InGaAsP layer and an InGaAs layer both of a first conductivity type in a recess formed in an InP substrate of the first conductivity type, forming InP of the first conductivity type on the surface and on the periphery thereof and forming a diffusion layer of a second conductivity type on the surface of the InP. CONSTITUTION:An n<->type InP layer 2 is formed on an n<+>type InP substrate 1. A trapezoidal portion of the layer 2 is etched away so that a recess is formed in the layer 2. An n<->type InGaAsP layer 3 and an n<->type InGaAs layer 4 are formed on the surface of the recess. Using resist formed on the recess as a mask, the structure is etched to be flattened. A P-type impurity is diffused in the surfaces of the layers 4 and 3 to form a p<+>type InGaAs layer 5 and a p<+>type InGaAsP layer 6. A P-type impurity is diffused through the layer 3 into the layer 2 with an insulation film used as a mask, so that a P-type InP layer 7 is formed. Then a Ti-Pt-Au film 8 is vapor deposited and a protection film 10 is formed over the whole surface.
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