DFT-Informed Kinetic Monte Carlo Simulation of Multiphase Thin Film Growth

Multiphase thin films grown via Pulsed Laser Deposition (PLD) technique have gained a significant attention in recent years due to their unique physical functionalities. In films with pillar-in-matrix configurations, vertical interfaces induce interesting physical, optical and chemical properties. Despite extensive experimental reports on multiphase film growth, a theoretical comprehension of the growth mechanisms and the influence of structure on properties is still lacking. In the case of growth morphology, it is known that both kinetic and thermodynamic factors are important but the relative roles of these factors are not yet understood. In this seminar, we report on a recently developed multiscale computational model of film growth. This model is based on kinetic Monte Carlo (kMC) simulation of film deposition and growth that is informed by Density Functional Theory (DFT) parameterization of diffusion and bonding energetics, and a continuum solution of the elastic strain arising from mismatch in the heterogeneous film system. The elastic problem resulting from lattice and thermal mismatch between the substrate, matrix and pillar materials is cast in the form of Representative Volume Element (RVE) with average constraints and solved using Fast Fourier Transform (FFT). The kMC simulations reveal the impact of the PLD growth conditions on the output morphology. Furthermore, DFT investigations of the impact of strain on the bonding and diffusion of adatoms/molecules on the surfaces reveal that the local strain can play a significant role in the phase separation mechanism of oxide-metal systems. The simulations are performed for Au-CeO₂ film system deposited on SrTiO₃ (001) substrate.