SEMICONDUCTOR PHOTO DEVICE

PROBLEM TO BE SOLVED: To improve sensitivity of a semiconductor photo device. SOLUTION: A photo-IC 1 is constituted of a substrate 2, an epitaxial laminate 3, a diffusion layer 4, a passivation film 5, and two electrodes 6 and 7. The laminate, 3 is composed of a first epitaxial layer 3a formed on the surface of the substrate 2 and a second epitaxial layer 3b laminated upon the layer 3a. At prescribed spots of the layers 3a and 3b, isolation layers 11a and 11b are respectively formed. A light receiving section 12 is constituted of the specific regions of the epitaxial layers 3a and 3b, surrounded by the isolation layers 11a and 11b. On the joint surfaces of the epitaxial layers 3a and 3b in the light receiving section 12, diffusion layers 4 are formed. Therefore, the light receiving section 12 is made into a laminated structure.