实验条件对纳米多孔SiO_2薄膜结构及特性的影响

EFFECT OF EXPERIMENTAL CONDITIONS ON THE STRUCTURE AND PROPERTIES OF NANO-POROUS SILICA FILMS

报道了实验制备条件对纳米多孔SiO2 薄膜结构、折射率、红外吸收、XPS等特性的影响 ,尤其是报道了一种新的快速、方便、有效实现纳米多孔SiO2 薄膜折射率连续调节的方法 .在溶胶 凝胶基础上 ,采用碱、酸一步法以及碱 /酸两步法和浸渍镀膜技术制备了纳米多孔SiO2 薄膜 .使用原子力显微镜、扫描电镜、XPS、傅里叶红外光谱仪、椭偏仪等方法测量和分析了薄膜的特性 .实验结果给出从碱一步法、碱 /酸两步法、到酸一步法形成的薄膜 ,SiO2 颗粒变小 ,孔隙率降低 ,折射率从 1 18连续增加到 1 41;Si2 p峰向高束缚能方向移动 ,并接近块体的值 ;红外吸收光学模ω4 的频率向低波数方向移动 ,揭示了Si O Si键角的不断降低 .这些结果表明 ,碱 /酸两步法能方便、有效地连续控制纳米多孔SiO2 薄膜的结构 ;实验条件对薄膜特性的影响起因于纳米多孔结构改变引起的SiO2 结构变化 .

The evolution of structure and properties of nano-porous silica films was investigated under different experimental conditions. A new method to adjust refractive index of the films rapidly and continuously is reported. The thin films were prepared with the base,acid one-step and base/acid two-step catalytic sol-gel processes and the dip-coating method. The structure and properties of the films were analyzed by atom force microscopy,scanning electron microscopy, X-ray photo electron spectroscopy, Fourier transform infrared, ellipsometry, separately. From the base one-step, the base/acid two-step,and the acid one-step catalytic process,silica particles in the films become small, the porosity decreases,and the refractive index increases continuously from 1.18 to 1.41.XPS analysis has shown Si2p peak shifts to a higher binding energy and near that of the silica bulk. The frequency shift of omega (4)(transverse optical mode) of infrared absorption to a lower wave number indicates a decrease in the average Si-O-Si bridging angle. These results suggest that the effect of the above experimental conditions on properties of nano-porous silica films is attributed to the change of the silica structure of the films.