Patent ID: 7811913

Claim:
A method of fabricating a low, dark-current germanium-on-silicon PIN photodetector, comprising: preparing a P-type silicon wafer; implanting the P-type silicon wafer with boron ions; activating the boron ions to form a P+ silicon surface region on the silicon wafer; forming a boron-doped germanium layer on the P+ silicon surface, including in-situ deposition of a doped p-type germanium layer, wherein the dopant is boron at a concentration is between about 5·10 17 cm +3 to 2·10 20 cm −3 , and wherein the thickness of the layer is between about 50 nm to 500 nm; depositing an intrinsic germanium surface layer on the boron-doped germanium layer; cyclic annealing, including heating in a first anneal step at a temperature of about 880° C. for about five minutes, followed by heating in a second anneal step at a temperature of about 760° C. for about five minutes, and repeating the first and second anneal steps for about twenty cycles, thereby forcing crystal defects to the boron-doped germanium layer; implanting ions in the germanium surface layer to form an N+ germanium surface layer and a PIN diode; and activating the N+ germanium layer by thermal anneal.