Instabilities at vicinal crystal surfaces - competition between the electromigration of the adatoms and the kinetic memory effect

TL;DR

This paper investigates the competing effects of electromigration and kinetic memory on step instabilities during sublimation and growth of vicinal crystal surfaces, revealing two distinct step bunching instabilities and illustrating a dynamical phase transition.

Contribution

It introduces a new model that captures the interplay between electromigration and kinetic memory effects without relying on the quasi-static approximation.

Findings

Identified two types of step bunching instabilities: density waves and coarsening.

Demonstrated the role of electromigration in step bunching with coarsening.

Illustrated the Popkov-Krug dynamical phase transition in surface dynamics.

Abstract

We studied the step dynamics during sublimation and growth in the presence of electromigration force acting on the adatoms. In the limit of fast surface diffusion and slow kinetics of atom attachment-detachment at the steps we formulate a model free of the quasi-static approximation in the calculation of the adatom concentration on the terraces. Numerical integration of the equations for the time evolution of the adatom concentrations and the equations of step motion reveals two different step bunching instabilities: 1) step density waves (small bunches which do not manifest any coarsening) induced by the kinetic memory effect and 2) step bunching with coarsening when the dynamics is dominated by the electromigration. The model developed in this paper also provides very instructive illustrations of the Popkov-Krug dynamical phase transition during sublimation and growth of a vicinal crystal surface.