Photodetector and radiation detector

A photodetector comprising:

• a substrate with a first face and a second face that is opposite to the first face;
• a plurality of pixels disposed to the substrate,
• each pixel including:
• a plurality of light detection cells disposed on the first face of the substrate, each light detection cell having a first terminal and a second terminal that connect to the substrate, each light detection cell being surrounded by a first opening having a continuous closed curve shape formed on the second face when viewed from a side of the second face of the substrate:
• a first wiring line disposed on the first face of the substrate to connect to the first terminal of each of the light detection cells;
• a first insulating film covering the second face of the substrate and a side face of a second opening disposed on the second face of the substrate, and penetrating the substrate to expose a part of the first wiring line, and a side face and a bottom of the second opening;
• a plurality of first electrodes, each of the plurality of the first electrodes being disposed in corresponding one of third openings and connected to the second face of the substrate, the third openings being disposed in the first insulating film and exposing a part of respective regions of the light detection cells in the second face of the substrate:
• a second electrode disposed on the second face of the substrate and connecting the plurality of the first electrodes;
• and
• a light blocking material filled to the first opening.