DIFFUSION OF ADSORBATE ATOMS ON THE RECONSTRUCTED SI(111) SURFACE

We study the adsorption and diffusion of foreign atoms with different valences (K, Mg, Ga: Gel on the reconstructed Si(111) surface using de nsity functional theory total-energy calculations. We End that the sta ble adsorption sites for all the adsorbate atoms considered are high-c oordination surface sites (T-4-type, H-3-type or B-2-type) rather than the surface dangling bond sites (T-1 or adatom T-4 site) as might hav e been expected from simple bond-counting arguments. We also examine t he surface diffusion paths and find that the adsorbate atoms, dependin g on their interaction with the surface, experience certain restrictio ns in their motion which we refer to as ''intermittent diffusion''. Th ese results help elucidate a number of experimental observations. (C) 1998 Elsevier Science B.V.