基底显微结构对薄膜生长影响的Monte Carlo模拟研究

Monte Carlo simulation and study of effect of substrate microstructure on thin film growth

利用Monte Carlo方法研究了基底显微结构对薄膜生长的影响.对不同显微结构基底上薄膜生长的初始阶段岛的形貌和尺寸与薄膜覆盖度和入射粒子沉积速率之间的关系进行了模拟和分析.模型中考虑了粒子沉积、吸附粒子扩散和蒸发等过程.结果表明,基底显微结构对薄膜生长具有明显影响.当沉积温度为300 K、沉积速率为0.005 ML/s(Mono1ayer/second,简称ML/s)、覆盖度为0.05 ML时,四方基底上薄膜生长呈现凝聚生长.随着覆盖度增加,岛的尺寸变大,岛的数目减少.而对于六方基底,当覆盖度从0.05 ML变化到0.25 ML时,薄膜生长经历了一个从分散生长过渡到分形生长的过程.无论是四方还是六方基底,随着沉积速率的增加,岛的形貌由少数聚集型岛核分布状态向众多各自独立的离散型岛核分布状态过渡.

The effect of the substrate microstructure on the thin film growth is studied by Monte Carlo method. The change of the island morphology and size at the early stage of the thin film growth with coverage and deposition rate on different microstructure substrates are simulated and analyzed. In our model,three processes are considered： particle deposition, adatom diffusion and adatom reevaporation. The result shows that the microstructure of the substrate has an obvious effect on the thin film growth. With the coverage of 0.05 ML,the thin film growth on the tetragonal substrate has been taken on condensation at the temperature of 300 K and the deposition rate of 0. 005 ML/s（Monolayer/second,ML/ s）. With coverage increasing,the mean size of islands becomes larger and its number is decreased. But for the hexagonal substrate,the island growth transits from sporadic to fractal shape with coverage increasing from 0.05 ML to 0.25 ML. With increase of deposition rate,facial morphology of the thin film on the tetragonal and hexagonal substrates changes from distributing state of collective and handful islands to one of numerous and discrete islands.