Capture numbers and islands size distributions in models of submonolayer surface growth

TL;DR

This study combines kinetic Monte Carlo simulations and rate equations to analyze capture numbers and island size distributions in submonolayer surface growth, revealing morphology-dependent behaviors and coverage effects.

Contribution

It provides detailed dependence of capture numbers on island size, morphology, coverage, and D/F ratio, and validates rate equations against simulations for various morphologies.

Findings

RE-ISDs agree with KMC-ISDs for all morphologies at low coverage.

Agreement diminishes for compact islands above 5% coverage due to coalescence.

Limiting curves for scaled island size distributions are coverage-independent for point islands.

Abstract

The capture numbers entering the rate equations (RE) for submonolayer film growth are determined from extensive kinetic Monte Carlo (KMC) simulations for simple representative growth models yielding point, compact, and fractal island morphologies. The full dependence of the capture numbers on island size, and on both the coverage and the D/F ratio between the adatom diffusion coefficient D and deposition rate F is determined. Based on this information, the RE are solved to give the RE island size distribution (RE-ISD). The RE-ISDs are shown to agree well with the corresponding KMC-ISDs for all island morphologies. For compact morphologies, however, this agreement is only present for coverages smaller than about 5% due to a significantly increased coalescence rate compared to fractal morphologies. As found earlier, the scaled KMC-ISDs as a function of scaled island size approach, for fixed coverage, a limiting curve for D/F going to infinity. Our findings provide evidence that the limiting curve is independent of the coverage for point islands, while the results for compact and fractal island morphologies indicate a dependence on the coverage.