Photo diode providing high-linearity signal current in response to light receiving signal

摘要

A photo diode in which an optical absorption layer and a p-type semiconductor layer neighboring on each other are designed to be at almost the same valence band level (their offset not exceeding 0.05 eV). Preferably the optical absorption layer is a GaInAsP layer with an absorption edge wavelength of 1.65 to 1.55 mu m, and the p-type semiconductor layer and lattice-matching with the preceding semiconductor layer are each an AlGaInAs layer with an absorption edge wavelength of 1.55 to 1.30 mu m remaining shorter than that of the optical absorption layer.