A computer simulation of nucleation and growth of thin films

Abstract

A three-dimensional kinetic Monte Carlo technique has been developed for simulating the nucleation and growth of thin films. The model involves incident atom attachment, surface diffusion of the atoms on the growing surface and atom detachment from the growing surface. Related effects caused by atom diffusion were taken into account. A significant improvement in calculation of activation energy for the atom diffusion was made based on a reasonable assumption of interaction potential between atoms. Trace files were created during the simulation and snapshots showing the morphology of the nucleation and growth of the thin films were taken by computer graph technique. The results showed that the density of the nucleus decreases and the size of island nucleation increases with increasing the substrate temperature and decreasing the deposition rate. At the meantime, a transition from two-dimension to three-dimension nucleation was observed. There exist three critical temperatures at a certain deposition rate: T n at which the nucleation rate reaches maximum, T r at which the surface roughness minimizes and T d at which the relative film density saturates. The three critical temperatures are functions of the deposition rate. The nucleation rate is close to constant under lower temperatures while it increases with deposition rate at higher temperatures. The film surface roughness depends on the density of island nucleation, it increases with temperature at lower temperatures and decreases at higher temperatures. The relative film density decreases with increasing the deposition rate.