DETERMINATION OF COMPLEX REFRACTIVE-INDEX AND THICKNESS OF A HOMOGENEOUS LAYER BY COMBINED REFLECTION AND TRANSMISSION ELLIPSOMETRY

Analytic inversion of combined reflection and transmission ellipsometric data is demonstrated. When the thickness is eliminated between the equations that give the reflection and transmission ratios rho = r(p)/r(s) and tau = t(p)/t(s), an algebraic equation for the unknown dielectric constant epsilon of the layer is obtained. After removal of some factors, this reduces to a linear equation in epsilon. The solution for unsupported films agrees with that previously obtained by Azzam [J. Phys. (Paris) C10, 67 (1993)]; it can be simplified to epsilon = epsilon1 sin2 theta1/(cos2 theta1 -rho/tau), where epsilon1 is the dielectric constant of the ambient medium and theta1 is the angle of incidence. Stability of the solution with respect to noise in the data is analyzed.