The determination of the optical constants of thin films from measurements of normal incidence reflectance and transmittance

Abstract

When the optical constants n and k of a thin film are calculated from the measured normal incidence reflectance and transmittance (R and T) by a successive approximation method, the results are complicated by multiple solutions and critical points of the equations R(n,k)=0 and T(n,k)=0 in the n,k plane. A method is given which enables the physical solution to be determined and which provides solutions in regions near the critical points where the successive approximation method is very inaccurate. The method, which combines Kramers-Kronig analysis of the transmittance data with the successive approximation method, is illustrated by results of measurements on an amorphous Mg-Sb alloy.