Computed energetics for etching of the Si(1 0 0) surface by F and Cl atoms

Energetics and limited reaction pathways have been computed using density functional theory with the B3LYP functional for the reaction of F and Cl atoms with the Si(1 0 0) surface. The energetics are in good agreement with the earlier ab initio calculations of Wu and Carter for the bonding of 1–3 F atoms to a surface dimer. The present energetics are also in good agreement with the results of Srivastava et al. using the Stillinger–Weber potential. We find no barrier for adding a third F atom to a monofluorinated dimer. A significant new result is a low energy pathway to SiF4, which has not been previously characterized. We find that Cl differs from F in having smaller binding energies and much larger non-bonded repulsions. Adding a third Cl to a monochlorinated dimer leads to a barrier of about 0.6 eV (for a symmetry constrained search) and step edge sites are strongly favored in the Cl case, but not in the F case. The energetics obtained for Cl on Si(1 0 0) are in good agreement with results obtained by Halicioglu and coworkers using the Feil potential.