Determination of Optical Constants of Thin Films from Measurements of Reflectance and Transmittance

A new approach to determine the optical constants of thin films using a single wavelength light source without measurement of film thickness has been introduced in this paper. From the reflectance and transmittance measured over a range of film thicknesses, the optical constants of as-deposited GeSbTe alloy films at a wavelength of 685 nm as well as the film thickness at each point of measurement have been obtained by use of a nonlinear fitting. A self-consistent validation of the approach is also presented by comparing the optical constants obtained in both cases of film-incidence and substrate-incidence.