Patent ID: 7871854

Claim:
A method for making a photodetector, the method comprising: forming a first opening in a top surface of a semiconductor substrate; performing an implant into the top surface of the semiconductor substrate to form a doped region; epitaxially growing a first semiconductor layer in the first opening along a bottom of the first opening and along sidewalls of the first opening, wherein the epitaxially growing the first semiconductor layer comprises in-situ doping the first semiconductor layer; filling the first opening with a dielectric material; forming a second opening in the dielectric material, wherein a bottom of the second opening exposes the epitaxially grown first semiconductor layer and sidewalls of the second opening expose the dielectric material; and filling the second opening with a semiconductor material, wherein the semiconductor material comprises a top electrode and a bottom electrode, wherein: the bottom electrode is in electrical contact with the first semiconductor layer epitaxially grown along the bottom of the first opening, the first semiconductor layer epitaxially grown along the bottom of the first opening is in electrical contact with the first semiconductor layer epitaxially grown along the sidewalls of the first opening, the first semiconductor layer epitaxially grown along the sidewalls of the first opening is in electrical contact with the doped region, the dielectric material in the first opening is located between sidewalls of the semiconductor material and the first semiconductor layer grown along the sidewalls of the first opening, and the doped region is laterally adjacent the semiconductor material.