Improved method for determination of optical constants of organic thin films from reflection and transmission measurements

A new technique for determining the optical properties of organic thin film s is presented. A detailed evaluation of the accuracy of the determined opt ical constants has been performed, and the best combination of measured val ues yielding the smallest errors in the index of refraction for realistic e xperimental uncertainties has been found. The proposed method utilizes the fact that optical constants are smooth continuous functions, which reduces the possibility of encountering multiple solutions. The method consists of two steps. In the first step the optical constants at all wavelengths and t he him thickness are determined. In the second step the thickness and the i maginary part of the index of refraction are kept fixed while we reevaluate the real part of the index of refraction by using a different objective fu nction with improved sensitivity to the refractive index. After verifying t hat the proposed method is capable of an accurate estimation of optical con stants, we determine the index of refraction data of vanadyl phthalocyanine in the visible spectral range. (C) 2000 Optical Society of America.