Ab initio investigation of C incorporation mechanisms on Si(001)

Ab initio calculations were performed to investigate adsorption and diffusion of C on the Si(001) surface at different surface and subsurface sites. Incorporation mechanisms of both substitutional and interstitial C during film deposition and growth were proposed. A surface diffusion process resulting in interstitial C incorporation was identified and the calculated energy barrier of ∼1.0 eV is consistent with the experimental value of 0.94±0.04 eV. The results support experimental observations of several groups: higher growth rates and lower temperatures favor the substitutional C incorporation.