Monte Carlo Simulations Of Thin Film Growth At Initial Stage

In recent years, the nano-film materials have attracted more and more attention due to their special material forms and performances. Thin films are obtained by film growth generally, the complicated processes of atoms'motion and the interactions of these processes during the film growth have a great influence on the crystal structures and performances of films. Therefore, these dynamic behaviors are necessary to research at atomic scale. With the rapid development of computer simulation technology, the mutual guidance action of theoretical and experimental investigations of thin film growth has been strengthened.Based on the research of microcosmic processes and methods of thin film growth, the models, including two-dimensional growth, three-dimensional growth and alloy thin films growth, are presented with periodic boundary conditions according to the existing models and by using the Monte Carlo method in this paper. Three principal dynamic processes in the description of thin film growth, deposition, diffusion and re-evaporation are considered independently, which means each of the three processes will take place in one Monte Carlo step according to their probabilities respectively, and the diffusion and re-evaporation are affected by the deposition. It is obtained from the analysis and simulations that the fabrication factors have an important effect on the growth of thin films.The results indicate that with the increase of the substrate temperature, the mobility of adatoms increases, it is shown as the transitions of island morphologies from dispersed growth, fractal growth to compact growth in submonolayer growth and growth modes from island growth to layer growth in three-dimensional growth, and the island morphologies are similar to the crystal lattice structures of the substrate at higher temperature. The deposition rate has an opposite influence on film growth, that is to say, the morphologies by reducing the deposition rate is similar to that by increasing temperature. The island morphologies will transit from fractal to compact with the energy of the nearest neighbors reducing. The Ehrlich-Schwoebel (ES) barrier controls the growth modes, that is with the increase of ES barrier, the movement of an adatom to diffuse down a surface step becomes increasingly difficult, this leads to the transitions of growth modes from island growth to layer growth.