Influence of an adsorbate on the morphology of a vicinal surface: sulfur on Cu(1 1 11), a STM and helium diffraction study

The adsorption of sulfur atoms on Cu(1 1 11) is shown to alter the step mobility and morphology. S atoms are adsorbed preferentially on kink sites, on the upper side of steps. The kink density increases with sulfur coverage and S-decorated kinks are immobile. The mobility of steps is correspondingly reduced although we have seen that the density of bare kinks is also enhanced for low S coverage.