Patent ID: 7875946

Claim:
A semiconductor photodetector comprising: a mesa structure formed on a first semiconductor layer of a first conduction type formed on a semiconductor substrate, said mesa structure having a bottom portion and a top portion that is narrower than the bottom portion; the top portion of said mesa structure including: a light absorbing layer, formed on said first semiconductor layer, for absorbing light; an electric field buffer layer, formed over said light absorbing layer, for buffering an electric field intensity; an avalanche multiplication layer, formed on said electric field buffer layer, for causing avalanche multiplication to occur; and a second semiconductor layer, formed on said avalanche multiplication layer, of a second conduction type, wherein said avalanche multiplication layer includes a central portion positioned in the center of said mesa structure, a side portion positioned in the vicinity of a side face of the top portion of said mesa structure, and an inclined portion positioned between the central portion and the side portion, a thickness of the inclined portion varying toward the side portion, an upper surface of the side portion of said avalanche multiplication layer is more inferior than an upper surface of the central portion of said avalanche multiplication layer, a side face of the side portion of said avalanche multiplication layer constitutes a part of the side face of the top portion of said mesa structure, and said second semiconductor layer is in contact with each of the upper surface of the central portion, the upper surface of the side portion and an upper surface of the inclined portion of said avalanche multiplication layer.