Optical properties of vacuum-deposited silver films have been investigated by ellipsometry. A method of calculating optical parameters has been developed and applied to this investigation. On the assumption that the film is optically isotropic, n, k, and d are simultaneously determined by the measured values of ψ, Δ, and the transmittance of p-polarized light. For very thin films, those isotropic parameters show an anomalous behavior, and for thinner films, the computation for determining them does not converge. The computation converges only when the optical anisotropy of the film is taken into account, and the convergent range of the anisotropic parameters is determined. The convergence range includes the anisotropic parameters predicted by the theory for the optical properties of an aggregated silver film. An anomalous increase of the isotropic parameters with decrease of thickness, for thinner films, arises from regarding the anisotropic film as isotropic.
TOMUO YAMAGUCHI, SADAFUMI YOSHIDA, and AKIRA KINBARA, "Effects of Optical Anisotropy of Aggregated Silver Films on Ellipsometric Determination of n, k, and d," J. Opt. Soc. Am. 62, 634-638 (1972)