Optical diagnostics of anisotropic nanoscale films on transparent isotropic materials by integrating reflectivity and...

The reflection of s- and p-polarized electromagnetic plane waves from an anisotropic ultrathin dielectric film on transparent isotropic substrate is investigated in the long-wavelength limit. The analytical approximate formulas are obtained for the reflection coefficients and ellipsometric angles that agree with the exact computer solution of the reflection problem for anisotropic systems. The possibilities of using the obtained expressions for resolving the inverse problem for ultrathin anisotropic dielectric films upon isotropic dielectric substrates are discussed. It is shown that a promising technique for determining the optical constants of anisotropic dielectric films on transparent substrates is the integration of ellipsometry and differential reflectivity.