High Quality N+/P Junction of Ge Substrate Prepared by initiated CVD Doping Process

For the first time, a novel co-doping scheme of P and Sn into Ge substrate using an initiated CVD (iCVD) dopant-containing polymer film is successfully developed. This optimized doping process provides high carrier concentration n-type doping of 3 $\times 10^{20}\mathrm{cm}^{-3}$ with a shallow junction depth of 50 nm. The enhancement of the P carrier concentration is attributed to less point defect generation during dopant injection and the strain relief effect induced by Sn co-doping with P into the Ge substrate. The Ge nMOSFETs with co-iCVD doping at the source/drain regions show lower off-state leakage current, higher on-current values, and lower contact resistivity compared to the Ge nMOSFETs with conventional ion implantation.