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Non-equilibrium Interface and Surface Dynamics

Realistic Multi-site Multi-component Lattice-gas Modeling for Epitaxial Growth of Metal Films on Binary Alloy Surfaces

James W. Evans

Iowa State University


Deposition of metals on binary alloy (rather than single component) crystalline substrates provides new possibilities for guiding the formation of far-from-equilibrium functional nanostructures, and also for fundamental studies of alloy self-growth [1,2]. Realistic treatment of non-equilibrium morphologies requires accurate description of terrace, edge, detachment, and interlayer diffusion. For single-component films where adatoms populate a single type of adsorption site, one can build a reasonable general form for hopping barriers with limited key DFT input. However, for adspecies populating multiple adsorption sites and especially for multi-component films, there are a vast number of island edge configurations for which one must accurately describe, e.g., edge diffusion. Here, we develop an alterative general formulation for hopping barriers which requires as input adspecies interactions for adatoms at both adsorption sites and transition states. These approaches are used to develop atomistic models for deposition of Ag, Au, Ni, and Al on NiAl(110), including co-deposition of Ni and Al to study alloy self-growth. The models are efficiently analyzed by KMC simulation to elucidate experimental observations.

[1] Y. Han et al. PRL 100 (2008) 116105; PRB 81 (2010) 115462
[2] T. Duguet et al., PNAS (2010) Special Issue on Surface Chemistry