| 摘要 |
PROBLEM TO BE SOLVED: To uniformize an output of an APD element by relaxing an electric field applied to a multiplication layer of an outside avalanche photodiode element, in a back-illuminated avalanche photodiode array.SOLUTION: A light incident part of a semiconductor substrate 2 is made thin. In the semiconductor substrate 2 on the opposite side of the light incident side of the back-illuminated APD array 1, an anode extraction layer 22 is formed at the periphery of the semiconductor substrate, and a plurality of APD elements 21 are formed at the light incident part to constitute an APD array 20. Each of APD element 21 has a cathode layer 211 and the multiplication layers 212 and 2121, and an pn junction is formed at an interface between the cathode layer 211 and the multiplication layers 212 and 2121. The multiplication layer 2121 of the outer APD element 21 is constituted as an electric field buffer layer 2121 by a fine pattern containing a plurality of islands. |
