Patent ID: 8120061

Claim:
A light receiving device, comprising: an InP substrate; and a light receiving layer formed by alternately stacking a larger layer formed of GaInNAsSbP mixed crystal having nitrogen content of at most 5% in 5 group, larger lattice constant (a) than that of the InP substrate (a 0 ) and thickness between hc and 11hc, the critical thickness hc being determined as hc=b(1−ν cos 2 α){log(hc/b)+1}/8πf(1+ν)cos λ (log being natural logarithm, b=a/2 1/2 , ν representing Poisson ratio, f representing lattice mismatch (a−a 0 )/a 0 with InP, cos λ=0.5, cos α=0.5) and a smaller layer formed of GaInNAsSbP mixed crystal having nitrogen content of at most 5% in 5 group, smaller lattice constant (a) than that of the InP substrate (a 0 ) and thickness between hc and 11hc; wherein absolute value of lattice mismatch of the larger layer and the smaller layer to the InP substrate is at least 0.5% and at most 5% respectively; at least one of the larger layer and the smaller layer has absorption edge wavelength of 2.0 μm to 3.0 μm; total thickness of the smaller layers and total thickness of the larger layers are each 2.0 μm to 4.0 μm; and average lattice mismatch obtained by multiplying lattice mismatch by thickness and averaging is at most ±0.2%.