Bonding behavior of metal atoms on Si surfaces

Abstract

In this paper we suggest a quantitative approach for description of the bonding behavior of the individual metal atoms on Si surfaces. It is proposed to use the relative contribution of electronic and ionic components of the effective polarizability of the metal atom to characterize the type of bond. Individual As, Sb, Na atoms adsorbed on $\mathrm{Si}(001)2\ifmmode\times\else\texttimes\fi{}1$ surface and K atoms adsorbed on both $\mathrm{Si}(001)2\ifmmode\times\else\texttimes\fi{}1$ and $\mathrm{Si}(111)7\ifmmode\times\else\texttimes\fi{}7$ surfaces were studied. It was found that the bonding behavior of the potassium on these two surfaces is completely different. The covalency parameters calculated according to this approach allow one to define the As-Si and Sb-Si bonds as almost pure covalent, Na-Si bond as polarized covalent, K-Si bond in the $\mathrm{Si}(001)2\ifmmode\times\else\texttimes\fi{}1$ surface as largely ionic, while in the $\mathrm{Si}(111)7\ifmmode\times\else\texttimes\fi{}7$ surface it is predominantly covalent.