First-principles total-energy calculations were presented for C incorporation in the H-saturated Si(100)2H-(1 x 1) surface. A large variety of atomic configurations involving 1, 2 and 4 substitutional C impurities in surface and sub-surface sites was considered. While C incorporation in the surface layer was energetically favored, C-C interactions played an important role and could stabilize configurations that would be otherwise unlikely, particularly configurations with C atoms in the 5th layer, as observed in recent X-ray photoelectron-spectroscopy experiments.

Energetics of Substitutional Carbon in Hydrogenated Si(100). P.Sonnet, A.Selloni, L.Stauffer, A.De Vita, R.Car: Physical Review B, 2002, 65[8], 085322 (6pp)