Non-conserved dynamics of steps on vicinal surfaces during electromigration-induced step bunching

TL;DR

This paper investigates the complex non-conserved dynamics of steps on vicinal surfaces during electromigration, revealing phenomena like interrupted coarsening, anticoarsening, and periodic switching influenced by sublimation and step interactions.

Contribution

It introduces new equations for step dynamics under electromigration and sublimation, capturing non-linear, non-conservative effects and explaining diverse surface evolution behaviors.

Findings

Identification of non-conservative terms in step equations

Observation of interrupted coarsening and anticoarsening

Detection of periodic switching between step bunches

Abstract

We report new results on the non-conserved dynamics of parallel steps on vicinal surfaces in the case of sublimation with electromigration and step-step interactions. The derived equations are valid in the quasistatic approximation and in the limit $f^{-1}\gg l_D\gg l_{\pm} \gg l_i$, where $f$ is the inverse electromigration length, $l_D$ the diffusion length, $l_{\pm}$ the kinetic lengths and $l_i$ the terrace widths. The coupling between crystal sublimation and step-step interactions induces non-linear, non-conservative terms in the equations of motion. Depending on the initial conditions, this leads to interrupted coarsening, anticoarsening of step bunches or periodic switching between step trains of different numbers of bunches.