【作者】 闫常瑜；

【导师】 王英龙；

【作者基本信息】 河北大学 ， 光学， 2006， 硕士

【摘要】 本工作首先假定烧蚀粒子与环境气体原子为刚性硬球,根据脉冲激光沉积纳米Si薄膜的原理,采用了Monte Carlo方法,对烧蚀粒子在环境气体中的输运过程进行了数值模拟。研究了不同靶衬间距情况下烧蚀粒子的速度分布,发现随着靶衬间距的增长,所制备的纳米Si薄膜的平均晶粒尺寸有先减小然后逐渐增大的趋势,在3cm左右处纳米晶粒的平均尺寸最小。而后实验研究了在Ar环境下靶衬间距的变化对所制备的纳米Si薄膜材料中晶粒平均尺寸的影响,利用脉冲激光烧蚀(PLA)技术,分别在Si(111)衬底和玻璃基片上制备了纳米Si薄膜,并通过扫描电子显微镜(SEM)、X射线衍射(XRD)以及拉曼散射(Raman)等技术,对所沉积的纳米Si薄膜的表面形貌以及晶态成分进行了分析和表征,结果表明:通过改变靶衬间距可以控制纳米Si晶粒的平均尺寸,所形成的纳米Si晶粒的平均尺寸随着靶衬间距值的增加先减小而后增大,靶衬间距为3cm时达到最小值,约为5nm;本文提出的由温度对应的速度方均根值来确定成核区间的方法,对激光烧蚀动力学的研究有一定的理论参考价值。更多还原

【Abstract】 On the basis of the theory of deposition of Si films by pulsed laser, and supposing the atoms of ablated vapor and ambient gas may interact as elastic hard-sphere,the transport process of ablated vapor in the ambient gas has been successfully simulated by adopting Monte Carlo method in the work. Varying the substrate-to-target distance, the velocity distribution of those collision particles are taken into account. With increasing the substrate-to-target distance, we have found the average size of the Si nanoparticles first decreases and reaches its minimum at about 3cm, and then increases . And then we studied the influence of substrate-to-target distance on the properties of nc-Si film deposited in high purity gas of Ar. Nanocrystalline silicon films are prepared by pulsed laser ablation (PLA) on Si (111) and glass substrates. Several measuring techniques, including Scanning electronic microscopy (SEM), X-ray diffraction (XRD) and Raman Scattering spectroscopy (Raman), are used to analyze the morphology characteristic and component and microstructure of the nanocrystalline silicon films. The results indicate that the average size of the Si nanoparticles is controlled by adjusting the substrate-to-target distance; with increasing gas pressure, the average size of the nanoparticles first decreases and reaches its minimum (50nm) at 3cm, and then increases. A new theory is also proposed to search nucleation area through the root mean square of velocity which deduced from the temperature, and we provide some reference for the study of the vapor dynamic model of the Si films deposition by pulsed laser ablation.更多还原