A 10.6 Micron Modulated Light Ellipsometer
A modulated light ellipsometer capable of measurements from the Ultraviolet to the infrared with particular emphasis on 10.6 μm has been developed for measuring the refractive index and absorption coefficient of bulk materials and thin films. This paper describes in detail the operating principles of the Hughes Research Laboratories ellipsometer and the specialized optical components required to permit operation of the instrument at 10.6 μm: a waveguide CO2 laser, ZnSe wiregrid polarizers, ZnSe acousto-optic modulator, and PbSnTe detector. In contrast to manual ellipsometers, phasesensitive amplifiers are employed to process the signal received at the detector, and the standard ellipsometric parameters are derived from the signals at the fundamental and second harmonic of the modulator and the DC signal. An analysis of sources of error and the limits of sensitivity of this instrument will be presented.
KeywordsZinc Quartz Fluoride Tungsten Iodide
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