SEMICONDUCTOR PHOTODETECTOR

PURPOSE:To obtain an InP/InGaAsP series avalanche photodiode in a high yield rate and manufacturing yield by separately arranging a P-N junction from the hetero junction boundary between a GaAsP light absorbing layer and an InP multiplication layer, and setting the electric field intensity in the region where a misfit dislocation exists to a value not higher than the specific value. CONSTITUTION:A misfit dislocation is produced (introduced) in a region 14A approx. 0.5mum within an InP multiplication layer 14 from the boundary between an N type InGaAsP light absorbing layer 13 and the layer 14. This dislocation is performed at 60 deg. from (11) and (1-10) directions. Thus, the depth of the P type InP layer formed by the diffusion of cadmium, i.e., the position of the P-N junction is set to the position where is isolated from the region where the misfit dislocation is produced. In other words, such P-N junction is arranged in the depth of 1mum from the surface of a P type InP layer 15. In an APD having this configuration, the reverse withstand voltage VB is 100V, the quantum efficiency is approx. 50%, and a dark current is 20-40nA at the voltage of 90% of the VB irrespective of the presence or absence of the misfit dislocation.