The Study Of Cluster Growth Processes By Direct Simulation Monte Carlo Method In Cluster Sources

Thin films obtained by cluster deposition have attracted strong attention as a new manufacturing technique to realize thin film material that can't be produced in usual way in the temperature that is lower than that of molecular beam epitaxial method. At present, high performance metallic materials, semiconductor, oxide, sulfide, organic films are produced by this technique. Because the film's features are influenced by the cluster properties, so the study of the clusters growth processes is very important. In this paper, the factors affecting the growth of cluster are studied by direct simulation Monte Carlo method in gas aggregation cluster source and magnetron sputtering-gas aggregation cluster source and the program is compiled by Fortran language, the model is self-build. The content of this paper could be concluded as following:1. In a gas aggregation cluster source, the size distributions of the Cu clusters in various experimental conditions such as growth length, out wall temperature and concentration of the inert gas are studied by direct simulation Monte Carlo method. The results show that size of cluster increases with the increase in the growth length, the size increases with the decrease in temperature and the number of big clusters decreases on increasing the concentration of the inert gas. Large clusters can be obtained after addition of He to the Ar in the same concentration of the inert gas.2. In a gas aggregation cluster source, the size distributions of the Cu clusters in various sizes and central positions of the exit nozzle and the change of the number of clusters in the chamber with the increase in time are studied by direct simulation Monte Carlo method. The results show that that size of cluster increases with the decrease in the diameter of the exit nozzle; larger clusters can be obtain in this situation that the central positions deviate the origin of the coordinates; the number of clusters in the chamber increases with the increase in time in the initial stage; soon after that, the number of clusters in the chamber decreases with the increase in time.3. In a magnetron sputtering-gas cluster source, the size distributions of the Cu clusters in various concentrations of the positive Cu or negative Cu gas are studied by direct simulation Monte Carlo method. The results show that the size distribution of clusters with no charge becomes narrower and the concentration and the maximum size of clusters with no charge become larger with the increase in the concentration of the positive Cu or negative Cu gas, oppositely the concentrations of clusters with positive or negative increase with the increasing of the concentration of the positive Cu, and then decrease comparing with having not charged Cu clusters in gas aggregation cluster source; the concentrations of clusters with positive or negative are roughly the same in the initial situation with same concentration. The main output is the negative clusters when the concentration of the negative Cu gas is larger than the concentration of the positive Cu gas; when the increasement of the concentration of the Cu gas, the size distribution of the negative Cu clusters becomes narrower.