Permeability and kinetic coefficients for mesoscale BCF surface step dynamics: discrete 2D deposition-diffusion equation analysis

TL;DR

This paper develops a discrete 2D model for step flow on vicinal surfaces, analyzing how permeability and kinetic coefficients depend on system parameters like kink density and diffusion barriers.

Contribution

It introduces a detailed discrete model that explicitly incorporates kinks and asymmetries, providing new insights into step flow dynamics and associated coefficients.

Findings

Permeability and kinetic coefficients vary with kink density and attachment barriers.

Explicit modeling of kinks affects adatom flux and density at step edges.

System parameters significantly influence surface growth behavior.

Abstract

A discrete version of deposition-diffusion equations appropriate for description of step flow on a vicinal surface is analyzed for a two-dimensional grid of adsorption sites representing the stepped surface and explicitly incorporating kinks along the step edges. Model energetics and kinetics appropriately account for binding of adatoms at steps and kinks, distinct terrace and edge diffusion rates, and possibly asymmetric barriers for attachment to steps. Analysis of adatom attachment fluxes as well as limiting values of adatom densities at step edges for non-uniform deposition scenarios allows determination of both permeability and kinetic coefficients. Behavior of these quantities is assessed as a function of key system parameters including kink density, step attachment barriers, and the step edge diffusion rate.