Kinetic step bunching during surface growth

TL;DR

This paper investigates the kinetic instability of step bunching during surface growth on anisotropic surfaces, revealing how elastic interactions and step parameter variations induce instability and coarsening, with growth rate dependence on flux.

Contribution

It introduces a model for step bunching instability considering anisotropic diffusion and elastic interactions, with predictions validated by numerical simulations.

Findings

Step bunching occurs on Si(001) and Ge(001) during epitaxial growth.

Maximal growth rate scales with the fourth power of deposition flux.

Numerical simulations show long-term coarsening behavior.

Abstract

We study the step bunching kinetic instability in a growing crystal surface characterized by anisotropic diffusion. The instability is due to the interplay between the elastic interactions and the alternation of step parameters. This instability is predicted to occur on a vicinal semiconductor surface Si(001) or Ge(001) during epitaxial growth. The maximal growth rate of the step bunching increases like $F^{4}$, where $F$ is the deposition flux. Our results are complemented with numerical simulations which reveals a coarsening behavior on the long time for the nonlinear step dynamics.