Island Size Selectivity and island-shape analysis during 2D Island Coarsening of Ag/Ag (111) Surface

TL;DR

This study uses kinetic Monte Carlo simulations to analyze island shape stability and size selectivity during Ag/Ag(111) surface coarsening, revealing that kinetically stable, closed-shell island shapes drive size distribution patterns.

Contribution

It provides a detailed analysis linking island shape stability to size selectivity, highlighting the role of kinetically stable closed-shell structures in coarsening dynamics.

Findings

Selected island sizes correspond to kinetically stable closed-shell shapes.

Stable shapes have a closed-shell structure with atoms having at least three neighbors.

Shape stability influences the island size distribution during coarsening.

Abstract

In our earlier study of Ag island coarsening on Ag(111) surface using kinetic Monte Carlo (KMC) simulations we found that during early stages coarsening proceeds as a sequence of selected island sizes resulting in peaks and valleys in the island-size distribution and that this selectivity is independent of initial conditions and dictated instead by the relative energetics of edge-atom diffusion and detachment/attachment processes and by the large activation barrier for kink detachment. In this paper we present a detailed analysis of the shapes of various island sizes observed during these KMC simulations and show that selectivity is due to the formation of kinetically stable island shapes which survive longer than non-selected sizes, which decay into nearby selected sizes. The stable shapes have a closed-shell structure - one in which every atom on the periphery having at least three nearest neighbors. Our KMC simulations were carried out using a very large database of processes identified by each atom's unique local environment, the activation barriers of which were calculated using semi-empirical interaction potentials based on the embedded-atom method.