Collective diffusion on a stepped substrate

Abstract

We present results for the collective diffusion of adatoms on a stepped substrate with submonolayer coverage. We study the combined effect of additional binding at the step edge, the Schwoebel barrier, enhanced diffusion along step edges, and 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 the analytical Green's function techniques. The collective effects due to finite coverage turn out to be crucial in determining the influence of steps on the macroscopic diffusion constant. The effect of steps turns out to be considerable for a much lower step density than previously anticipated.