Phosphorus (P) atomic layer doping of SiCe was realized by low pressure (rapid thermal) chemical vapor deposition. We control the incorporation of the dopant through the surface adsorption equilibrium of PH3. P profiles of less than one monolayer can be obtained at very low temperature (room temperature up to 400 degrees C). The P coverage in relation to the PH3 partial pressure was analyzed according to Langmuir’s adsorption isotherm. An effective activation energy of 0.30 eV was estimated from the investigation of the temperature dependence of the incorporated P concentration in the temperature range between 200 degrees C and 400 degrees C. This activation energy is discussed in terms of temperature dependent surface adsorption equilibrium. The incorporated P concentration measured by secondary ion mass spectrometry is compared with the concentration of electrically active net dopants found from Hall effect measurements.