Multiphysics approaches for modeling nanostructural evolution during physical vapor deposition of phase-separating alloy films

Abstract

Physical vapor deposition of phase-separating alloy films yields a rich variety of distinct self-assembled nanostructures depending on the deposition rate and temperature. However, the role of grain boundaries, elastic imhomogeneity, and anisotropy, and surface tension, in the formation of such nanostructures is currently not well understood. Here, we employ a phase-field approach that couples the multiphysics of elemental diffusion, elastic misfit and anisotropy, surface tension, and grain boundaries with processing parameters, namely deposition rate and temperature, to investigate phase separation and grain boundary evolution in binary alloy films. We develop phase-field deposition models of increasing complexity to isolate and analyze the influence of processing parameters on nanostructural transitions in vapor co-deposited films. While it is found that such transitions are primarily guided by a minimization of total free energy, our simulation-based insights strongly indicate the phenomena of nanostructure selection at faster deposition rates. It is anticipated that the insights gained from this study will provide the much-required knowledgebase for establishing nanostructure-level control in the physical vapor deposition of alloy films.