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采用脉冲激光烧蚀技术,在室温、低压Ar气条件下通过改变气体压强及靶与衬底间距,对纳米Si晶粒成核的气压阈值进行了研究.根据扫描电子显微镜图像、拉曼散射谱和X射线衍射谱对制备样品的表征结果,确定了在室温、激光能量密度为4J/cm2、靶与衬底间距为3cm条件下形成纳米Si晶粒的阈值气压为0.6Pa.结合流体力学模型和成核分区模型,对纳米晶粒的成核动力学过程进行了分析.通过Monte Carlo数值模拟,表明在气相成核过程中,烧蚀Si原子的温度和过饱和密度共同影响着纳米晶粒的成核.
By using pulsed laser ablation technique, the gas pressure threshold of nano-Si nucleation was studied by changing the gas pressure and the distance between target and substrate under room temperature and low pressure Ar gas.According to scanning electron microscope image, Raman scattering spectrum And X-ray diffraction spectra were used to characterize the prepared samples. The threshold pressure of forming nano-Si grains at room temperature, laser energy density of 4 J / cm 2 and target-substrate spacing of 3 cm was determined to be 0.6 Pa. Combining with the fluid mechanics model And nucleation zoning model were used to analyze the nucleation kinetics of nanocrystalline grains. Monte Carlo numerical simulation shows that the temperature and supersaturation density of ablated Si atoms affect the nanocrystalline grains The nucleation.