Breakdown of step-flow growth in unstable homoepitaxy

TL;DR

This paper investigates two mechanisms causing the breakdown of step-flow growth in homoepitaxy, using kinetic Monte Carlo simulations and scaling arguments to analyze island nucleation and vacancy island formation.

Contribution

It identifies and characterizes two distinct breakdown mechanisms in step-flow growth, highlighting the roles of island nucleation and step meandering.

Findings

Island nucleation leads to mound formation under inhibited interlayer transport.

Vacancy islands form due to self-crossing of meandering steps.

Vacancy island spacing scales with the square of the meander wavelength.

Abstract

Two mechanisms for the breakdown of step flow growth, in the sense of the appearance of steps of opposite sign to the original vicinality, are studied by kinetic Monte Carlo simulations and scaling arguments. The first mechanism is the nucleation of islands on the terraces, which leads to mound formation if interlayer transport is sufficiently inhibited. The second mechanism is the formation of vacancy islands due to the self-crossing of strongly meandering steps. The competing roles of the growth of the meander amplitude and the synchronization of the meander phase are emphasized. The distance between vacancy islands along the step direction appears to be proportional to the square of the meander wavelength