Determination of optical parameters and thickness of weakly absorbing thin films from reflectance and transmittance spectra

A method for determining the optical constants and the thickness of weakly absorbing thin films on substrates is proposed. In this method only the reflectance and transmittance spectra obtained at a single arbitrary angle of incidence are used, provided that the former reveals several interference extrema. The calculation procedure is based on relatively simple relations suitable for the programmed realization and does not call for the prescription of the initial values of the parameters to be determined. The method proposed is fairly accurate and allows one to uniquely solve the inverse problem of spectrophotometry. The optical constants and the thickness of an As(x)Se(y) film formed on a glass substrate have been determined by the proposed method in the visible region of the spectrum.