Adatom diffusion on vicinal surfaces with permeable steps

TL;DR

This study investigates how adatoms diffuse on vicinal surfaces with permeable steps, revealing how step permeability, kink spacing, and kinetic asymmetries influence atom incorporation and diffusion patterns.

Contribution

It provides a detailed analysis of adatom diffusion dynamics considering step permeability, kink spacing, and Ehrlich-Schwoebel effects, highlighting their combined impact on atom behavior.

Findings

Step permeability increases with kink spacing.

Ehrlich-Schwoebel barrier suppresses step permeability.

Permeability events scale with kink spacing.

Abstract

We study the behavior of single atoms on an infinite vicinal surface assuming certain degree of step permeability. Assuming complete lack of re-evaporation an ruling out nucleation the atoms will inevitably join kink sites at the steps but can do many attempts before that. Increasing the probability of step permeability or the kink spacing lead to increase of the number of steps crossed before incorporation of the atoms into kink sites. The asymmetry of the attachment-detachment kinetics (Ehrlich-Schwoebel effect) suppresses the step permeability and completely eliminates it in the extreme case of infinite Ehrlich-Schwoebel barrier. The average number of permeability events per atom scales with the average kink spacing. A negligibly small drift of the adatoms in a direction perpendicular to the steps leads to a significant asymmetry of the distribution of the permeability events the atoms thus visiting more distant steps in the direction of the drift.