CALCULATION OF THIN-FILM OPTICAL-CONSTANTS BY TRANSMITTANCE-SPECTRA FITTING

Our investigation uses the film-interference transmittance spectrum in the computer calculation of thin-film thickness t and complex refract ive index n = n - ik. Titanium oxide films of different thicknesses a re studied, and a new approach to determine the film thickness and opt ical constants is proposed. This new approach is based on the use of n umerical optimization methods in transmittance-spectra fitting. Variou s dispersion equations of the finite-power-series type are used to obt ain the best fit between transmittance measurements and calculations. The best-fit results for n(lambda) and k(lambda) are found to agree wi th dispersion relations that follow from a quantum theory of light abs orption. (C) 1998 Optical Society of America.