Patent ID: 8294234

Claim:
A mesa photodiode comprising: a stack structure that is formed on a semiconductor substrate, said stack structure comprising: a buffer layer comprising a semiconductor of a first conductivity type; an etching stopper layer comprising a semiconductor of a second conductivity type, formed above said buffer layer; a light-absorbing layer comprising a semiconductor of the second conductivity type, formed above said etching stopper layer; a double-layer semiconductor layer of the second conductivity type formed above said light-absorbing layer; a multiplication layer that is stacked and grown on said buffer layer and comprises a semiconductor of the first conductivity type or an undoped type, and a field buffer layer that is stacked and grown on said multiplication layer and comprises a semiconductor of the second conductivity type, said double-layer semiconductor layer of the second conductivity type and said light-absorbing layer forming a mesa, a sidewall of said mesa being an inclined surface that is inclined in a direction in which a bottom of said mesa becomes wider, at least said sidewall of said mesa being covered with a semiconductor layer that is grown on said sidewall, said semiconductor layer being of the first conductivity type, the second conductivity type, a semi-insulating type, or the undoped type, an inclined angle of said inclined surface of said mesa at an upper end portion being smaller than an inclined angle of said inclined surface of said mesa at a lower end portion, and wherein said mesa photodiode comprises a mesa avalanche photodiode.