Diffusion on a stepped substrate

TL;DR

This paper investigates how steps on a substrate influence the collective diffusion of adatoms, revealing a significant impact that varies with step density and coverage, using analytical and simulation methods.

Contribution

It introduces a combined analytical and Monte Carlo approach to study diffusion on stepped substrates, highlighting the crossover from step-dominated to terrace-dominated diffusion.

Findings

Diffusion behavior depends strongly on step density and coverage.

Steps have a more pronounced influence on diffusion than previously thought.

A crossover from step-dominated to terrace-dominated diffusion is identified.

Abstract

We present results for collective diffusion of adatoms on a stepped substrate with a submonolayer coverage. We study the combined effect of the additional binding at step edge, the Schwoebel barrier, the enhanced diffusion along step edges, and the finite coverage on diffusion as a function of step density. In particular, we examine the crossover from step--dominated diffusion at high step density to terrace-dominated behavior at low step density in a lattice-gas model using analytical Green's function techniques and Monte Carlo simulations. The influence of steps on diffusion is shown to be more pronounced than previously anticipated.