SEMICONDUCTOR PHOTODETECTOR

摘要

PROBLEM TO BE SOLVED: To provide an inexpensive semiconductor photodetector which selectively receives light at longer wavelength side and has good characteristics. SOLUTION: This semiconductor photodetector 10 which selectively receives the longer-wave side light A of multiplexed light rays containing the light A and shorter-wave side light B is provided with a multilayered film 22 which is formed by alternately laminating materials having different refractive indexes upon another, by designing the thicknesses and numbers of the layers so that the film 22 may transmit the light A at the longer wavelength side and reflect the light B at the shorter wavelength side and a first light absorbing layer 14 constituted of a material having a longer band-gap wavelength than the light A has.