Domain formation in the deposition of thin films of two-component mixtures

• Published in: Journal of alloys and compounds 2020-09, Vol.835, p.155093, Article 155093
• Main Authors: To, Tung B.T., Aarão Reis, Fábio D.A.
• Format: Article
• Language: English
• Subjects: Adatoms; Computer simulation; Computer simulations; Connectivity; Deposition; Diffusion; Domain structure; Domains; Lattice parameters; Monte Carlo simulation; Nanostructured materials; Substrates; Terraces; Thin films
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.155093

We perform a kinetic Monte Carlo simulation study of a model of thin film deposition of two-component mixtures in which the activation energy for diffusion of an adatom is additive over its nearest neighbors and in which the interactions between adatoms of the same species are stronger than those between adatoms of different species. First, we consider a symmetric case in which the interactions of adatoms of the same species are the same for the two components. For low and intermediate temperatures, we show the formation of narrow domains which meander in the layers parallel to the substrate and which are connected through very long distances. The domain widths, which range between 3 and 30 lattice constants, depend on the ratio between the flux and diffusion coefficients of adatoms on terraces of the same species, on lateral interactions, and energy barriers at terrace edges, but are weakly affected by interactions of different species. We obtain scaling relations that can provide rough estimates of those widths using tabulated properties of films with a single component. At high temperatures, the separation of domains is enhanced, but their long distance connectivity is lost, which shows that the formation of the long meandering domains is restricted to a certain range of temperature and flux. Similar morphological features are obtained when the intra-species interactions are different and the adatom diffusion coefficients on terraces of the same species differ up to two orders of magnitude. An approximate scaling relation for the domain width is obtained and the species with the largest mobility constrains the temperature range in which the long connected domains are found. •Simulations of two-component thin film deposition show domain formation.•Meandering domains have nanoscale widths.•From low to intermediate temperatures, domains are connected at long distances.•Domain width can be estimated from single component interactions.