Island nucleation in metal thin-film growth

Island nucleation and growth during thin-film epitaxy is typically described using mean-field rate equations. Assuming that interactions between adatoms do not extend beyond the short range and that deposited atoms remain on top of the substrate, among other things, these equations can be solved to yield a scaling relationship that predicts the density of stable islands as a function of the deposition rate and the diffusivity of an isolated adatom Recent theoretical and experimental studies indicate that the assumptions behind this "standard" nucleation theory are not always upheld. Medium- and long-range interactions between adatoms may change the picture that nucleation theory provides. Also, intermixing of deposited atoms into the substrate can occur in heteroepitaxy. We review our recent theoretical studies, in which we have used density-functional theory calculations and kinetic Monte Carlo simulations to probe the initial stages of thin-film epitaxy for: (i) the growth of Ag on a strained Ag(111) surface and (ii) the growth of Cc on Cu(001). We discuss the "novel" growth modes in these systems and related experimental work.