Abstract
In general, crystal growth proceeds by the addition of growth units at steps originating from dislocations or 2D nuclei. However, evidence exists that small 3D nuclei deposited on crystal faces can also act as step sources. In this study, the Monte Carlo method, based on the Kossel model, is used to study the fates of 3D nuclei adsorbed on planar and stepped crystal surfaces. For equilibrium, Delta mu/kT = 0, the nuclei dissolve completely, regardless of size. For supersaturated solutions, Delta mu/kT > 0, the upper parts of the nuclei dissolve, while the lower parts act as a source of steps expanding over the surface. This results in flat topped growth islands, the slope of which side faces increases for increasing nucleus size and supersaturation and decreasing bond strength. Growth on stepped surfaces leads to the formation of approximately circular plateaus, the width of which increases with decreasing substrate slope. Upon continued growth, these plateaus evolve into bunched step patterns. The Monte Carlo simulations are supplemented with a semiquantitative model, which helps in explaining the features observed by the Monte Carlo method.
