Source-optics polarization effects on ellipsometry analysis

Analytical expressions for the Fourier coefficients are presented that permit the effects of source polarization to be included in the analysis of ellipsometric data for the inference of the optical properties of bulk samples. The developed expressions are general and can be obtained for any ellipsometer system as long as the source-optics characteristics are known. In addition, no constraints are imposed on the angle of incidence of the light beam and on the polarizer/analyzer azimuthal angles. We obtained measurements on an amorphous carbon sample at a temperature of 25 °C and in the 400-700-nm wavelength range and analyzed the data using the discrete Fourier transform. Comparisons were carried out for the inferred refractive indices with and without the source-polarization effects. We show that for the source optics and sample used in this study the real part of the index increases by 1.5% when the source-optics parameters are included, whereas the imaginary part of the index decreases by as much as 12%. Thus the correction should not be neglected when accurate values for the indices are to be obtained from the complex ellipsometric parameters of the sample surface.