Irreversible nucleation in molecular beam epitaxy: From theory to experiments

TL;DR

This paper advances the understanding of nucleation in molecular beam epitaxy by incorporating nonuniform barriers and steering effects, providing a more comprehensive model that aligns with experimental observations.

Contribution

It introduces a refined theoretical model of nucleation in MBE that accounts for barrier nonuniformity and steering effects, extending previous models.

Findings

Nonuniform Ehrlich-Schwoebel barriers significantly affect nucleation rates.

Steering effects alter atom trajectories and nucleation probabilities.

Model predictions align with experimental second layer nucleation data.

Abstract

Recently, the nucleation rate on top of a terrace during the irreversible growth of a crystal surface by MBE has been determined exactly. In this paper we go beyond the standard model usually employed to study the nucleation process, and we analyze the qualitative and quantitative consequences of two important additional physical ingredients: the nonuniformity of the Ehrlich-Schwoebel barrier at the step-edge, because of the existence of kinks, and the steering effects, due to the interaction between the atoms of the flux and the substrate. We apply our results to typical experiments of second layer nucleation.