Aspnes D E, Studna A A
Appl Opt. 1975 Jan 1;14(1):220-8. doi: 10.1364/AO.14.000220.
We describe the design, construction, alignment, and calibration of a photometric ellipsometer of the rotating-analyzer type. Data are obtained by digital sampling of the transmitted flux with an analog-to-digital converter, followed by Fourier transforming of the accumulated data with a dedicated minicomputer. With an operating mechanical rotation frequency of 74 Hz, a data acquisition cycle requires less than 7 msec. The intrinsic precision attainable is high because precision is limited only by shot noise or intrinsic source instabilities, even when relatively weak continuum lamps are used as light sources. Precision may be improved by accumulating the data for consecutive cycles at a fixed wavelength. The system allows complex reflectance ratios to be determined as continuous functions of wavelength from the near infrared to the near ultraviolet spectral range. Data reduction programs can be modified to calculate complex refractive index or dielectric function spectra, or film thicknesses and refractive indices, as well as the usual ellipsometric parameters tanpsi, cosDelta.
我们描述了一种旋转分析型光度椭圆仪的设计、构造、校准和对准。通过使用模数转换器对透射通量进行数字采样来获取数据，随后用一台专用小型计算机对累积数据进行傅里叶变换。在74Hz的工作机械旋转频率下，一个数据采集周期所需时间不到7毫秒。可达到的固有精度很高，因为精度仅受散粒噪声或光源固有不稳定性的限制，即使使用相对较弱的连续谱灯作为光源时也是如此。通过在固定波长下累积连续周期的数据，可以提高精度。该系统能够确定从近红外到近紫外光谱范围内作为波长连续函数的复反射率比。数据处理程序可以修改，以计算复折射率或介电函数光谱、薄膜厚度和折射率，以及常用的椭圆偏振参数tanψ、cosΔ。
