2D approximant lattice model: A framework for the simulation of amorphous film deposition

Abstract

A 2D approximant lattice model has been developed for Monte Carlo simulation of amorphous film growth via physical vapor deposition at low temperature. The model allows for structural randomness of the deposited film by introducing a distribution of bond angle and bond length for the bond between incoming and substrate atoms, and it reduces the computational cost by discretizing the simulation domain into lattice points. The model has been tested by investigating the effects of bond angle and bond length ranges and surface relaxation distance on microstructure and roughness evolution of the deposited film. Simulation results show that the increase in bond-angle and bond-length ranges increases the amorphousness of the deposited film, as expected, while surface relaxation distance mainly affects the film density and growth exponent β: the film density increases while β decreases with increasing surface relaxation distance. The advantage of this model is in its ability to model the deposition of both crystalline and amorphous structures in one framework. In addition, its flexibility allows for the incorporation of other growth-process details such as surface diffusion, which may be crucial, depending on the material and the process, as well as extension to 3D for investigating and controlling interfacial roughness in realistic multilayered systems.