BROAD-BAND SPECTROSCOPIC ELLIPSOMETRY BASED ON A FOURIER-TRANSFORM SPECTROMETER

An ellipsometer attachment for a commercially available Fourier transform spectrometer (Bruker IFS 66) was developed. Almost no modification of the basic spectrometer was necessary. The optical set-up, providing a parallel light beam with variable diameter, is placed in the sample compartment. The beam is deflected to an external goniometer attachment which allows measurements to be taken with incident angles of up to 85-degrees depending on the sample size. The possible combinations of our optical components (light sources, beam-splitters, polarizers, and detectors) allow measurements in the wavenumber range from 30 000 to 400 cm-1. The polarizers are aligned automatically. Determination of the refractive index of thin films is based on measurements at multiple angles of incidence and evaluation by the least squares fit method.