Multiple-Angle-of-Incidence Ellipsometry of Very Thin Films*

Abstract

To minimize random errors in measurements on very thin (<100 Å) Ag tarnish films where sensitivity is low because of film thickness, least-squares solutions with minimum residuals (MLSR) are used in estimating the optical constants and thickness. The range of acceptable MLSR values is reduced when the number of measuring angles is increased (from three to five in our measurements). The results are comparable to those obtained by curve fitting and have a wavelength dependence similar in form but lower in magnitude compared to published results on thicker, artificially grown Ag2S.