P atomic layer doping (P-ALD) of Ge is investigated at temperatures between 100°C and 300°C using a single wafer reduced pressure CVD system. Hydrogen-terminated and hydrogen-free Ge (100) surface are exposed to PH3 followed by Ge deposition at 300°C. P adsorption is suppressed by hydrogen-termination of Ge surface. On hydrogen-free Ge surface, incorporated P dose is increased with increasing PH3 exposure time and saturation behavior is observed. The saturation value of P by P-ALD at 300°C is 1.5e14 cm -2, which is close to a quarter of monolayer of Ge surface. The saturation value is not depending on PH3 partial pressure. The incorporated P dose is able to be described by Langmuir type kinetic. The electrical active P concentration of 6e19cm-3, which is 6 times higher active P concentration compared to solid solubility is obtained.