Semiconductor photo device

摘要

A semiconductor photo detector provided with a photo detecting portion, in which at least three semiconductor layers of the same conductivity type and different energy gaps are formed in the order of magnitude of the energy gap, and in which another semiconductor layer which has the same composition as a first semiconductor layer having the largest energy gap among the at least three semiconductor layers but is different in conductivity type from the first semiconductor layer is formed in contact with the first semiconductor layer at the optical input side of the semiconductor photo diode.