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对纳米硅薄膜的微结构研究一直是这个领域中令人感兴趣的问题.Mandelbrot提出的分形理论可用于材料显微结构的定量表征,而分形维数是描述分形结构特征的一个重要几何参量.近年来,人们利用光学显微镜和SEM等手段对薄膜材料和金属断口的表面形貌进行了很多研究,但由于实验手段的限制,通常只能获得材料在微米尺度上的分形特征,而且存在实验过程和数据处理繁琐等缺点.80年代初发展起来的STM,具有纳米量级乃至原子量级的分辨率,能够非破坏性地直接获得样品表面形貌的实空间三维图象,便于进行数据处理,从而使人们可较方便地在纳米乃至原子尺度上对材料的表面进行研究.我们首先采用STM在纳米尺度上对不同工艺条件下按常规PECVD技术制备的微晶及纳米硅薄膜的表面形貌进行了观测,并结合分形理论计算了样品表面形貌的分形维数D,从而找到了D值与样品微结构参数之间的联系.1 实验过程实验所用的硅薄膜样品是在常规PECVD系统中,使用高比例的高纯氢稀释的硅烷作为反应气体,利用RF+DC双重功率源激励等离子体辉光放电制备得到的.薄膜样品的厚度～1μm,衬底为普通的玻璃片.样品表面微观形貌的观测是采用CSTM-9000型STM(中国科学院化学研究所生产)在常温和大气中完成的.观测前,样品在稀释的HF中漂洗,以除去表面上的氧?
The microstructure research of nanostructured silicon thin films has always been an interesting issue in this field.Mandelbrot’s fractal theory can be used to quantitatively characterize the microstructure of materials, while fractal dimension is an important geometric parameter to describe the characteristics of fractal structure. In recent years, many studies have been made on the surface morphology of the film material and the metal fracture by means of optical microscope and SEM. However, due to the limitation of experimental methods, the fractal characteristics of the material at the micrometer scale are usually obtained, and the experimental process And data processing cumbersome and other shortcomings of the STM developed in the early 1980s with nano-level and even atomic resolution, non destructive direct access to the sample surface morphology of real space three-dimensional images for easy data processing, and thus So that people can more conveniently on the nanometer and even atomic scale on the surface of the material.We first STM using nanoscale on different process conditions according to conventional PECVD prepared microcrystalline and nano-silicon film surface morphology was Observation and fractal theory combined with fractal theory to calculate the surface morphology of the fractal dimension D, and thus find the D value and sample The relationship between the microstructure parameters of the product.1 The experimental process The silicon film samples used in the experiments were high-purity hydrogen-diluted silanes as reaction gases in a conventional PECVD system, and the plasma glow discharge was excited by the RF + DC dual power source The thickness of the film sample was ~ 1μm, and the substrate was an ordinary glass piece.The microstructure of the sample surface was observed at room temperature and in the atmosphere by CSTM-9000 STM (produced by Chinese Academy of Sciences) Before the sample is rinsed in diluted HF to remove the oxygen on the surface?