Monte Carlo Simulations And Experimental Study Of Thin Film Growth

With the development of modern technology, more and more research are focus on the nanometer thin films because of their unique performance, thin solid films are widely used in optoelectronic device, catalysis industry and other modern engineering fields. The nanometer thin film growth mechanism consists of atomic adsorption, adatoms growth of clusters, desorption and so on, quantities of studies show that the mechanism of thin film growth has deep impact on its performance, therefore it is a very necessary to study the film growth process in atomic scale. With the help of computer technology, the growth process that can’t be observed in experiment can be simulated.In this paper, we use numerical simulation and experimental research to analyze the film growth process in micro-scale, mainly discussing the effect of substrate temperature, deposition rate and other preparation conditions during the growth. In the aspect of simulation,3-D Monte Carlo model was presented. We simulated elemental silver film growth on triangular lattice substrate and NiTi alloy thin film growth on square lattice substrate. The growth was simplified to three independent processes; they were adsorption, diffusion and re-evaporation of different atoms on the substrate surface, the diffusion activation energy was calculated by embedded atom method. In the aspect of experiment, NiTi alloy films was prepared using RF magnetron sputtering equipment, in this method, pure Ni target and pure Ti target sputtered at the same time with the propose of controlling the number of the two atoms, the substrate rotated on its axis in the meantime to ensure the two atoms equally distributed.The simulated results showed that the substrate temperature and the deposition rate had a significant influence on transitions of island shape and the growth type. Increasing the substrate temperature and decreasing the deposition rate can lead the same trend for films, such as the size of islands increases, the roughness becomes less and the number of islands decreases meanwhile. The experiments results showed that for preparation of NiTi alloy films, when the substrate temperature risen to300℃, the composition of films maintained stable; with the deposition time increased, the adhesion of Ni atom decreased and even lead to films fragment; two atoms can be near equal as the sputtering power of Ni and Ti were30W and110W.