title: Spectroscopic null ellipsometer using a variable retarder.
abstract: We describe a polarizer-compensator-sample-analyzer (PCSA) null ellipsometer in which a variable retarder is used as the compensator and either the polarizer or the analyzer is held at a fixed azimuthal angle. Ellipsometric angles ψ and Δ are determined directly from the azimuth of the rotating component and the compensator delay, respectively. A Soleil-Babinet compensator with quartz plates is used as the variable delay element and the delay at any wavelength is calculated from the independently measured delay at 632.8 nm and a knowledge of the dispersion of quartz. The thicknesses of thin silicon dioxide films on a silicon wafer were determined both spectroscopically and at a single wavelength and show excellent agreement with those determined using a traditional single wavelength PCSA null ellipsometer.
authors.affiliation: Department of Physics, University of Auckland, P.B. 92019, Auckland, New Zealand. l.watkins@auckland.ac.nz
authors.forename: Lionel R
authors.initials: LR
authors.lastname: Watkins
authors.forename: Sophie S
authors.initials: SS
authors.lastname: Shamailov