Height-dependent barriers and nucleation in quantum size effect growth

TitleHeight-dependent barriers and nucleation in quantum size effect growth
Publication TypeJournal Article
Year of Publication2008
AuthorsKuntova Z, Tringides MC, Chvoj Z
Journal TitlePhysical Review B
Date Published10/01
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberISI:000260574400139

An analytic model is developed to model the growth of the uniform height islands. The formation of bilayer rings on top of stable islands and the absence of nucleation on top of the third layer are particularly intriguing. The analysis is motivated from recent Monte Carlo simulations that have reproduced the bilayer morphology. The analytic model allows better transparency to the role of the different barriers. In particular the diffusion anisotropy (i.e., atoms diffuse faster azimuthally within the ring than toward the island center) explains why nucleation is only observed close to the island edge and not in the middle. Lower barriers to diffuse back to the wetting layer from unstable heights than the barriers from stable heights explain the absence of nucleation on the third layer. The model can have general use in other systems where quantum size effects play a role and the barriers become height dependent.

Alternate JournalPhys. Rev. B