Revisiting step instabilities on crystal surfaces. Part II: General theory
arXiv:2101.02614 · doi:10.1016/j.jmps.2021.104582
Abstract
The quasistatic approximation is a useful but questionable simplification for analyzing step instabilities during the growth/evaporation of vicinal surfaces. Using this approximation, we characterized in Part I of this work the effect on stability of different mechanisms and their interplay: elastic step-step interactions, the Schwoebel barrier, and the chemical coupling of the diffusion fields on adjacent terraces. In this second part, we present a stability analysis of the general problem without recourse to the quasistatic approximation. This analysis reveals the existence of a supplementary mechanism, which we label the "dynamics effect" as it follows from accounting for all the convective and transient terms in the governing equations. This effect can be stabilizing or destabilizing depending on the ratio of step attachment/detachment kinetics to terrace diffusion kinetics. Further, we find that this dynamics effect remains significant in the slow deposition/evaporation regime, thereby invalidating the classical postulate underlying the quasistatic approximation. Finally, revisiting experiments of crystal growth on Si(111)-7x7 and GaAs(001), our analysis provides an alternative explanation of the observed step bunching, one that does not require the mechanisms previously invoked in the literature.
References in corpus (6)
- Crystal symmetry, step-edge diffusion and unstable growth
- Kinetics of step bunching during growth: A minimal model
- On the role of step-flow advection during electromigration-induced step bunching
- Instabilities at vicinal crystal surfaces - competition between the electromigration of the adatoms and the kinetic memory effect
- Evaporation and growth of crystals - propagation of step density compression waves at vicinal surfaces
- Scaling laws for step bunching on vicinal surfaces: the role of the dynamical and chemical effects