Small fluctuations in epitaxial growth via conservative noise

Abstract

We study the combined effect of growth (material deposition from above) and nearest-neighbor entropic and force-dipole interactions in a stochastically perturbed system of N line defects (steps) on a vicinal crystal surface in 1+1 dimensions. First, we formulate a general model of conservative white noise, and we derive sim- plified formulas for the terrace width distribution (TWD) and pair correlations, particularly the covariance matrix of terrace widths, in the limit N → ∞ for small step fluctuations. Second, we apply our formalism to two specific noise models which stem, respectively, from: (i) the fluctuation-dissipation theorem for diffusion of adsorbed atoms; and (ii) the phenomenological consideration of deposition-flux- induced asymmetric attachment and detachment of atoms at step edges. We discuss implications of our analysis, particularly the narrowing of the TWD with the de- position flux, connection of noise structure to terrace width correlations, behavior of these correlations in the macroscopic limit, and comparison of our perturbation results to a known mean field approach.