低压下气流对激光沉积纳米硅晶化及尺寸的影响

纳米硅具有明显的光致发光效应和量子尺寸效应,广泛的应用在现代电子工业和太阳能光伏工业中.尺寸影响着纳米硅的实际用途,因此制备尺寸可控的纳米硅晶粒具有很重要的实际意义.本文采用脉冲激光沉积(PLD)技术,在烧蚀点水平方向、距靶2 cm处引入一束流量为5 sccm的氩(Ar)气流,在0.01-0.5 Pa的Ar气压下烧蚀高阻抗单晶硅(Si)靶.在管口正下方1 cm处水平放置衬底来沉积纳米Si薄膜;并用同一装置,在0.08 Pa的Ar气压下分别引入流量为0,2.5,5,7.5,10 sccm的Ar气流沉积纳米Si薄膜.利用原子力显微镜(AFM)、X射线衍射(XRD)、Raman散射对样品表面形貌和微观结构进行分析表征.结果表明:不引入气流时出现纳米Si晶粒的阈值气压是0.1Pa,引入气流后出现纳米Si晶粒的阈值气压为0.05 Pa.晶粒尺寸随着气流流量的增大而减小.

Influence of gas flow on the size and crystal of silicon nanoparticle produced by laser deposition in low pressure

The nanocrystal silicon films were prepared by using a pulsed laser to ablate a high-resistivity single crystalline Si target in an ambient pressure range of 0.01-0.5 Pa of pure argon gas. An argon gas flow is introduced in the horizontal direction of the ablation point in an axial range of 2 cm. Nanocrystal Si films are deposited on glass or single crystalline (111) Si substrates placed at a distance of 1 cm below the nozzle. Then the same device is used to prepare the ranocrystal Si films at a pressure of 0.08 Pa with gas flow being, respectively, 0, 2.5, 5, 7.5, 10 sccm. The morphologies and microstructurs of the samples are characterized by atomic force microscopy (AFM), X-ray diffraction (XRD) and Raman scattering. The results show that the Si nanocrystal threshold pressure is 0.1 Pa without gasflow, and 0.05 Pa with gasflow. The size of Si nanocrystal decreases as the gasflow increases.