OPTICAL SEMICONDUCTOR DEVICE

PROBLEM TO BE SOLVED: To provide an optical semiconductor device which compatibly achieves an enhancement of a light receiving sensitivity, an increase of an operating speed, and a reduction of a noise. SOLUTION: The optical semiconductor device comprises: a semiconductor substrate 1; a light-receiving element 2 formed on the semiconductor substrate 1; a light-absorbing element 4 formed on the semiconductor substrate 1 and disposed adjacent to the light-receiving element 2; and a signal processing semiconductor element 3 formed on the semiconductor substrate 1. Further, the light-absorbing element 4 has a fifth semiconductor layer 29, and structures of light-absorbing regions differ between the light-receiving element 2 and the light absorbing element. COPYRIGHT: (C)2009,JPO&INPIT