Patent ID: 7151881

Claim:
An optical circuit comprising: a semiconductor substrate comprising silicon; an optical waveguide formed in or on the substrate, said optical waveguide comprising a core made of a SiGe alloy; and an optical detector formed in or on the semiconductor substrate, said optical detector aligned with the optical waveguide so as to receive an optical signal from the optical waveguide during operation, said optical detector having: a first electrode; a second electrode, wherein the first electrode comprises a first doped semiconductor material and the second electrode comprises a second doped semiconductor material and wherein the first and second doped semiconductor materials are of the same conductivity type; and an intermediate layer between the first and second electrodes, said intermediate layer comprising a semiconductor material characterized by a conduction band, a valence band that is at a lower energy level than the conduction band, and deep level energy states introduced between the conduction and valence bands.