TiO2薄膜表面粗糙度与散射特性研究

Surface Roughness and Scattering Characteristics of TiO2 Thin Film

通过电子束热蒸发技术在K9玻璃上镀制光学厚度为λ/4的TiO2薄膜,研究不同沉积速率和沉积角度对TiO2薄膜散射损耗的影响规律和机理,并利用TalysurfCCI白光干涉表面轮廓仪和Horos散射仪分别测量镀制前后薄膜表面粗糙度和双向反射分布函数。实验结果表明:TiO2薄膜表面粗糙度随着沉积速率的增大而减小,最终趋于0.88nm,且实验值都小于基底表面粗糙度1.5nm,说明TiO2薄膜可以降低基底表面粗糙度,具有平滑基底的作用。随着入射沉积角的增大,薄膜的表面粗糙度逐渐增大,当沉积角为0°和20°时,薄膜表面粗糙度小于基底表面粗糙度;当沉积角为40°和60°时,薄膜表面粗糙度大于基底表面粗糙度。薄膜表面散射量随表面粗糙度的减小而降低,两者具有正相关关系,实验数据与理论计算结果相吻合;当薄膜表面粗糙度小于基底粗糙度时,薄膜表面散射将低于裸基底的表面散射,可实现减散射的效果。

A TiO2 thin film with an optical thickness ofλ/4 is plated on K9 glass using the electron beam thermal evaporation technique.The effect and mechanism of different deposition rates and deposition angles on the scattering loss of TiO2 thin films are investigated.The surface roughness and bidirectional reflection distribution function of the TiO2 thin film before and after plating are measured using TalysurfCCI white light interference surface profiler and Horos scattering instrument.The results show that the surface roughness of the TiO2 thin film decreases as the deposition rate increases and eventually reaches 0.88 nm,which is less than the bare substrate surface roughness of 1.5 nm.This indicates that the TiO2 thin film can reduce the surface roughness of the substrate,and it is capable of smoothing the substrate.As the incident deposition angle increases,the surface roughness of the film gradually increases.When the deposition angles are 0°and 20°,the surface roughness of the film is less than that of the substrate;when the deposition angles are 40°and 60°,the surface roughness of the film is greater than that of the substrate.A positive correlation exists between the amount of surface scattering of the film and the surface roughness.Experimental data agree with theoretical calculations.When the surface roughness of the film is less than that of the substrate,the surface scattering of the film is lower than that of the bare substrate.Thus,TiO2 thin films can reduce surface scattering from the substrate.