Kinetic Monte Carlo simulation of chemical vapor deposition growth of thin films

We have implemented a 2D+1 solid-on-solid kinetic Monte Carlo (KMC) model to explore aspects of thin film growth via chemical vapor deposition (CVD) that may differ from growth via physical vapor deposition (PVD). This model is a minimal extension to CVD of models that have previously been used by others to successfully simulate MBE growth. This extension involves the introduction of a molecular species that has a relatively high surface mobility and dissociates, at a site-dependent rate, into an atomic species with a lower mobility that is subsequently integrated into the film. Introducing this molecular species can result in a non-monotonic dependence on growth temperature of film surface roughness. A similar non-monotonic dependence of film quality on temperature has been reported in CVD growth of high temperature superconductors. We also found a difference in film morphology between molecular-mobility controlled growth and atomic-mobility controlled growth that may indicate a difference in the fractal dimension of the surface. We have found two different mechanisms that cause this non-monotonic effect, the first relies solely on configuration dependent dissociation and the second combines both configuration dependent dissociation and atomic mobility. These results demonstrate that these KMC models can help to explain aspects of the differences between PVD and CVD.