Patent ID: 8399945

Claim:
A semiconductor light detecting element comprising: a semiconductor substrate; and a distributed Bragg reflector of a first conductivity type, an optical absorption layer, and a semiconductor layer of a second conductivity type, which are sequentially laminated on the semiconductor substrate, wherein the distributed Bragg reflector includes first semiconductor layers and second semiconductor layers which are alternately laminated, each first semiconductor layer has a band-gap wavelength which is longer than wavelength of detected light which is incident on and detected by the light detecting element, each second semiconductor layer has a band-gap wavelength which is shorter than the wavelength of the detected light, reflectance peak wavelength of the distributed Bragg reflector is in a range from 1.20 μm to 1.35 μm, band-gap wavelengths of the first semiconductor layers in the distributed Bragg reflector become shorter closer to the optical absorption layer and become longer further from the optical absorption layer, and average band-gap wavelength of the first semiconductor layers is in a range from 1.35 μm to 1.55 μm.