The effect of chalcogens (O, S) on coarsening of nanoislands on metal surfaces

In this article, we review some of our recent work concerning sulfur adsorption on Ag(1 1 1), and the effect of sulfur on coarsening of nanoscale Ag islands. We find that sulfur accelerates coarsening, but that a finite threshold coverage exists, below which the sulfur only decorates step edges and does not affect coarsening kinetics. Furthermore, below room temperature, and at coverages above the threshold, an ordered metal-sulfur adlayer structure develops. This structure contains long rows of Ag3S3 clusters as its dominant motif, and its development coincides with inhibition of coarsening. Taken in the context of published literature, these observations suggest that acceleration of coarsening of metal nanofeatures by adsorbed chalcogens is a general effect, and that metal-chalcogen clusters are the agents of metal mass transport. Possible models are discussed.