The present invention is based on the finding of the inventors that at the lattice mismatching degree Δa/a between the GaInAs light absorbing layer and the InP buffer layer in the positive range the dark current is lower than {HEAD ~ the negative range} at {TAIL ~ room temperature} 
The present invention is based on the finding of the inventors that at the lattice mismatching degree Δa / a between the GaInAs light absorbing layer and the InP buffer layer in the positive range the dark current is lower than { HEAD ~ the negative range } at { TAIL ~ room temperature }
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