Step Repulsion Mediates Wandering on a Si(001) Vicinal Face

TL;DR

This paper investigates how step repulsion influences wandering instability on Si(001) vicinal surfaces, revealing that repulsive interactions are essential for instability and groove formation, confirmed through analysis and simulations.

Contribution

It introduces a model showing that step repulsion is crucial for step wandering instability on anisotropic vicinal surfaces, supported by stability analysis and Monte Carlo simulations.

Findings

Step repulsion is essential for wandering instability.

In-phase wandering produces straight grooves.

Groove amplitude grows proportionally to the square root of time.

Abstract

With a Si(001) vicinal surface in mind, we study step wandering instability on a vicinal surface with an anisotropic surface diffusion whose orientation dependence alternates on each consecutive terrace. In a conserved system step wandering takes place with step-up adatom drift. Repulsive interaction between steps is found indispensable for the instability. Monte Carlo simulation with a strong repulsive step interaction confirms the result of linear stability analysis, and further shows that in-phase step wandering produces straight grooves. Grooves widen as their amplitudes increase in proportion to the square root of time.