Ge-Si P-I-N Photodiode With Reduced Dark Current And Fabrication Method Thereof

A method of forming a photodiode, comprising:

• forming a silicon-on-insulator (SOI) substrate;
• forming a bottom contact layer on the substrate, the bottom contact layer doped to exhibit a first conductive type by ion implantation;
• forming a thin silicon layer on the bottom contact layer by epitaxy;
• forming a relatively lighter doped region of the first conductive type on the thin silicon layer by ion implantation;
• forming an unintentionally doped germanium layer on the thin silicon layer by epitaxy;
• forming a bottom doped region of the germanium layer by thermal treating;
• forming a doped sidewall region of the germanium layer by ion implantation at a sidewall of the germanium layer;
• forming a thin amorphous silicon layer on the germanium layer;
• forming a top contact layer by ion implantation on the amorphous silicon layer, the top contact layer doped to exhibit a second conductive type, a doped region of the top contact layer is at least 1-um smaller than the doped sidewall region of the germanium layer;
• and
• forming an anti-reflection coating layer on the top contact layer by deposition.