椭偏光度法研究溶胶-凝胶SiO_2薄膜的光学性能

Spectroscopic Ellipsometry Characterization of Optical Properties for Sol-Gel Derived SiO_2 Film

用溶胶-凝胶工艺在碱性、酸性催化条件下制备具有纳米多孔结构的SiO2薄膜.用反射式椭圆偏振光谱仪测试薄膜的椭偏参数,并用Cauchy模型对椭偏参数进行数据拟合,获得了溶胶-凝胶SiO2薄膜光学常数在300～700 nm波段的色散关系.用场发射扫描电子显微镜FE-SEM研究了薄膜表面微结构,并讨论表面微结构与光学性能间的关系.结果表明:制备条件所引起的薄膜微结构差异对光学常数的色散关系变化趋势无影响;薄膜光学常数的大小则与微结构有关,折射率大小与薄膜孔洞率成反比.

The nano-porous SiO2 films with high laser damage threshold were prepared by using sol-gel process based on base and acid catalysis. Spectroscopic ellipsometer and FE-SEM were used to characterize the optical properties and surface microstructure of nano-porous SiO2 film. The Cauchy model was presented well in fitting spectroscopic ellipsometric data for the film optical constants. The film optical constants in 300-700 nm waveband are obtained and the relation between microstructure and optical constants is also discussed. The difference of microstructure has no effect on the dispersion relation of the films while it has effect on the value of the optical constants. The refractive index is inversely proportional to the porosity of the film.