Stability and diffusion of surface clusters

TL;DR

This paper investigates the thermal stability and diffusion behavior of surface adatom clusters using kinetic Monte Carlo simulations, revealing size-dependent diffusion and a phase transition leading to island disappearance at high temperatures.

Contribution

It introduces a combined kinetic Monte Carlo and bond-counting approach to analyze surface cluster stability and diffusion, highlighting size effects and phase transition characteristics.

Findings

Diffusion constant decreases with cluster size, approximately as N^{-1}

At high temperatures, a phase transition causes the island to vanish

Diffusion follows a power-law dependence on cluster size

Abstract

Using kinetic Monte Carlo simulations and a bond-counting ansatz, thermal stability and diffusion of an adatom island on a crystal surface are studied. At low temperatures, the diffusion constant $D$ is found to decrease for a wide range of island sizes like $D \propto N^{-\alpha}$, where $\alpha$ is close to one, $N$ being the number of adatoms in the cluster. By heating up the surface, the system undergoes a phase transition above which the island disappears. Characteristics of that transition are discussed.