A kinetic Monte Carlo simulation of chemical vapor deposition: non-monotonic variation of surface roughness with growth temperature

We have implemented a 2D+1 solid-on-solid kinetic Monte Carlo model to explore aspects of thin film growth via chemical vapor deposition (CVD) that may differ from growth via physical vapor deposition. This model is a minimal extension to CVD of models that have previously been used by others to successfully simulate growth by molecular beam epitaxy. 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.