New bonding configuration on Si(111) and Ge(111) surfaces induced by the adsorption of alkali metals

The structure of the (3 x 1) reconstructions of the Si(lll) and Ge(lll) 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 x 1) surface results primarily from the substrate reconstruction and shows a new bonding configuration consisting of consecutive fivefold and sixfold Si (Ge) rings in [110] projection separated by channels containing the alkali metal atoms.