Ab initio study on interaction between carbon atom and Si(1 0 0) surface in strong electric fields

The interaction potentials of atomic carbon on a Si(1 0 0)-p(2×2) in strong electric fields are obtained by the first-principles molecular dynamics method. The height of an adsorbed carbon atom is less than that of a Si adatom from the Si-surface-dimer owing to the small covalent radius of a carbon atom. The desorption energy of the carbon atom on the Si surface decreases from 5.4 eV in a zero field to 4.8 eV in a positive field of 1 V/Å, but it remains almost unchanged in a negative field of −0.5 V/Å. We found that the reduction of desorption energy of carbon atom in the electric field is smaller than that of silicon atom. This is interpreted in terms of electron affinities and ionization energies of carbon and silicon atoms.