Submonolayer growth with decorated island edges

TL;DR

This study uses kinetic Monte Carlo simulations to explore how impurities decorating island edges influence nucleation and growth dynamics, revealing that impurities increase island density but do not alter the expected scaling behavior.

Contribution

It introduces a detailed two-species growth model showing that impurity decoration affects island density without changing the scaling laws predicted by earlier theories.

Findings

Impurities increase island density during growth.

Decorated island edges do not act as effective attachment barriers.

Scaling of island density with flux remains unchanged.

Abstract

We study the dynamics of island nucleation in the presence of adsorbates using kinetic Monte Carlo simulations of a two-species growth model. Adatoms (A-atoms) and impurities (B-atoms) are codeposited, diffuse and aggregate subject to attractive AA- and AB-interactions. Activated exchange of adatoms with impurities is identified as the key process to maintain decoration of island edges by impurities during growth. While the presence of impurities strongly increases the island density, a change in the scaling of island density with flux, predicted by a rate equation theory for attachment-limited growth [D. Kandel, Phys. Rev. Lett. 78, 499 (1997)], is not observed. We argue that, within the present model, even completely covered island edges do not provide efficient barriers to attachment.