二氧化钒薄膜的变温红外光学特性研究

Study on Temperature Dependence of Infrared Optical Properties of Vanadium Dioxide Thin Film

基于二氧化钒在约68℃出现的半导体到金属的可逆相变,伴随有电学和光学特性的改变。因为相变机制的复杂性,很难从理论上推导出相变前后光学常数随波长和温度变化的解析表达式。研究了二氧化钒薄膜的折射率和消光系数的色散规律,借助于Sellmeier色散模型通过数值拟合,得出了二氧化钒变温的光学常数色散表达式。通过薄膜矩阵理论计算,获得了在不同温度和波长条件下的薄膜光学透射率和反射率。采用磁控溅射方法分别在玻璃、蓝宝石和二氧化硅衬底上制备了不同厚度的二氧化钒薄膜,测量了这些薄膜的光学透射率和反射率,结果表明,实验曲线与计算模拟曲线符合得很好。

Vanadium dioxide undergoes a reversible phase transition at approximately 68 ℃,and it is accompanied with drastic changes in its electrical and optical properties.It is difficult to get the accurate analytic expression dependent on temperature and wavelength through theoretical derivation,because phase transition mechanism is complex.Dispersion theory for refractive index and extinction coefficient of the vanadium dioxide thin film is studied,and its temperature-dependence dispersion formula of optical constants is presented by numerical fitting with Sellmeier dispersion model.By film matrix theory,the optical transmittance and reflectivity at different temperatures and wavelengths are calculated.In the use of magnetron sputtering,vanadium dioxide thin films of different thicknesses are deposited on glass,sapphire and silicon dioxide substrates.The optical transmittance and reflectivity of the films are measured,and the experimental curve agrees well with that of simulation.