【摘要】 利用准分子脉冲激光晶化非晶硅薄膜是制备高密度尺寸可控的硅基纳米结构的有效方法之一.本文将脉冲激光对非晶硅超薄膜的影响处理为热传导问题,采用了基于Tersoff势函数的分子动力学方法模拟了在非晶氮化硅衬底上2.7nm超薄非晶硅膜的脉冲激光晶化过程.研究了不同激光能量对非晶硅薄膜晶化形成纳米硅的影响,发现在合适的激光能量窗口下,可以获得高密度尺寸可控的纳米硅薄膜,进而模拟了在此能量作用下非晶硅膜中成核与生长的机理与微观过程,并对晶化所获得的纳米硅薄膜的微结构进行了分析.更多还原

【Abstract】 Laser crystallization of amorphous Si thin films is one of reliable method of preparing nanocrystalline silicon with high density and controllable size. In the present work,molecular dynamics simulation based on Tersoff potential was used to study the laser crystallization process of ultrathin amorphous silicon film (2. 7 nm) on amorphous silicon nitride substrate. The influence of laser fluences on the crystallization and formation of nanocrystalline Si was investigated. It was found that there exists a laser fluence window in which nucleation and growth of nanocrystalline Si can be realized,which is in agreement with our previous experimental observations. The nucleation and growth processes in microscopic scale were simulated and the size of formed nanocrystalline Si was limited in both vertical and lateral directions by the film thickness and the formation of grain boundaries.更多还原