双重傅里叶变换红外椭偏光谱系统的研制

Design of an Infrared Spectroscopic Ellipsometer Using Double-Fourier-Transform Method

介绍一种新型红外椭圆偏振光谱实验系统。实验中采用了对光子能量和方位角作双傅里叶变换 ,及同步旋转检偏和起偏器 (RAP)的方法 ,根据傅里叶变换的四个余弦交流分量 ,计算相应的光学常数。经过对实验系统各误差来源的分析和纠正 ,提高了实验精度 ,使误差控制在 1%以内。测量了Au等样品的红外介电函数谱 ,并用德鲁得 (Drude)模型作拟合运算 ,获得了与理论计算相一致的结果。

A new type of infrared spectroscopic ellipsometer has been designed and constructed. A double-Fourier-transform method, i.e. Fourier transforms carried out as both functions of the photon energy and azimuthal angle, is used. Using the configuration of synchronous rotation of the polarizer and analyzer (RAP), and according to four cosine frequencies of Fourier transform, the optical constants can be obtained with any one of two sets of AC signal calculations. After a revised model being used to correct the data error arising from the slight anisotropy of analyzer the data self-consistency is improved to be better than 1% by comparing two sets of data. The spectra of the dielectric function for a Au film sample were measured and fitted with the Drude model. The result shows a very good agreement between experiment and theory.