Patent ID: 6956251

Claim:
An on-p-GaAs substrate Zn 1-x Mg x S y Se 1-y avalanche photodiode for inducing avalanche amplification by a strong electric field formed by applying a reverse bias below a breakdown voltage, comprising: a p-GaAs single crystal substrate having a top surface and a bottom surface; a p-(ZnSe/ZnTe) m (m: integer denoting a number of pair layers) superlattice which is made by piling p-ZnSe thin films and p-ZnTe thin films reciprocally for changing bandgaps stepwise and is epitaxially grown on the top surface of the p-GaAs substrate; a p-Zn 1-x Mg x S y Se 1-y (0≦x≦0.8, 0≦y≦0.8) layer epitaxially grown on the p-(ZnSe/ZnTe) m superlattice or via a p-ZnSe buffer layer upon the p-(ZnSe/ZnTe) m superlattice; a lower-doped n − -Zn 1-x Mg x S y Se 1-y (0≦x≦0.8, 0≦y≦0.8) layer epitaxially grown on the p-Zn 1-x Mg x S y Se 1-y layer; a higher-doped n + -Zn 1-x Mg x S y Se 1-y (0≦x≦0.8, 0≦y≦0.8) layer epitaxially grown on the lower-doped n − -Zn 1-x Mg x S y Se 1-y layer; a metallic n-electrode which is formed upon a part of the higher-doped n + -Zn 1-x Mg x S y Se 1-y layer and has a top aperture for allowing incidence light to enter; and a metallic p-electrode formed on the bottom surface of the p-GaAs substrate.