Kinetic Monte Carlo Simulation Of The Thin Film Epitaxial Growth

The micro movement of cluster deposited and the microstructure evolution of thin film have been studied under the atom-cluster scale in this paper. There are the great significance in refining and optimizing the deposition processes, improving the thin film qualities and perfecting its properties when the research was done on the migration, deposition and nucleation of atoms.In this paper, basing on the researches of microcosmic processes and thin film growth methods, we considered the existing models and numerically simulated two-component film epitaxial growth processes with the kinetic Monte Carlo method. In the simulation we chose a given number of one-dimensional flat lattice as the substrate and employed the periodic boundary condition for the growth surface boundary problem. Mainly we considered the kinetic processes of the deposited atom absorption and absorbed atom diffusion. By analyzing and simulating, we knew that the interatomic bond energies and the growth temperature have the important effect on the thin films growth. The simulation results showed that only when the interatomic bond energies satisfy the condition(EAA+EBB-2EAB)>0, can the film growth tend to phase separation and form nanoculsters. On the basis of these results, we also simulated the influence of growth temperature to the morphology of nanostructures and gave the results of the suitable growth temperatures forming the well nanoculsters. If the growth temperature was in a low level, the diffusibility of atoms was relatively weak and deposited atoms has not reached on the position with a stable energy then another new atom was deposited which resulted in hardly form large clusters. If the growth temperature was in a high level, the absorption energy is relatively higher and the deposited atoms were easy to desorption out of the clusters bound to form the single-atom distribution or small clusters.Finally, we simulated the action of surfactant atoms floating upward in the growth system. The simulation results showed that this surfactant action on the growth temperature has a particularly sensitive critical point. Only when the growth temperature was over the critical point will the surfactant atoms float upward. When the temperature kept on rising, due to the diffusion of atoms was enhanced, that induced the increasing upward floating of the atoms and the growing of a smooth film surface. We also found that the selection of the substrate has a significant influence in the morphology of the films. When the substrate was not specially involved (atoms deposited randomly), the B atoms tended to exchange atoms with the A atoms on the same layer and the thin films grew and formed nano-columns. When considering the substrate (A atoms deposited on first layer), the B atoms turned to an excellent surfactant and tended to exchange atoms with the upper layer A atoms which showed that the film growth mode of the B atoms has upward floating action.