Spiral surface growth without desorption

TL;DR

This paper investigates spiral surface growth in epitaxial thin films where adatom desorption is negligible, using numerical phase-field simulations and analytical methods to predict step spacing and relaxation times.

Contribution

It introduces a non-local diffusion model for spiral growth in the no-desorption limit, providing new quantitative predictions distinct from local theories.

Findings

Predicted step spacing as a function of deposition flux

Analyzed relaxation time dependence on dislocation density

Identified differences from local limit predictions

Abstract

Spiral surface growth is well understood in the limit where the step motion is controlled by the local supersaturation of adatoms near the spiral ridge. In epitaxial thin-film growth, however, spirals can form in a step-flow regime where desorption of adatoms is negligible and the ridge dynamics is governed by the non-local diffusion field of adatoms on the whole surface. We investigate this limit numerically using a phase-field formulation of the Burton-Cabrera-Frank model, as well as analytically. Quantitative predictions, which differ strikingly from those of the local limit, are made for the selected step spacing as a function of the deposition flux, as well as for the dependence of the relaxation time to steady-state growth on the screw dislocation density.