New Bonding Configuration on Si(111) and Ge(111) Surfaces Induced by the Adsorption of Alkali Metals

The structure of the (3×1) reconstructions of the Si(111) and Ge(111) surfaces induced by adsorption of alkali metals has been determined on the basis of surface x-ray diffraction and low-energy electron diffraction measurements and density functional theory. The (3×1) surface results primarily from the substrate reconstruction and shows a new bonding configuration consisting of consecutive fivefold and sixfold Si (Ge) rings in 〈11̄0〉 projection separated by channels containing the alkali metal atoms.