A structure and method of making an N-FET with a highly doped source/drain and strain booster are presented. The method provides a substrate with a Ge channel region. A gate dielectric is formed over the Ge channel and a gate electrode is formed over the gate dielectric. Sacrificial gate spacers are disposed on the sidewalls of the gate dielectric and gate electrode. Cavities are etched into the substrate extending under the sacrificial gate spacers. Si1-xGex source/drain regions are doped in-situ during formation, x