Inversion of transmission ellipsometric data for transparent films.

Transmission ellipsometry measures the real and imaginary parts of the ratio τ = t(p)/t(s), where t(s), and t(s) are the transmission amplitudes for thep and s polarizations. For a homogeneous layer, the unknowns to be determined are the layer dielectric constant ε = n(2) and the layer thickness Δz. For nonabsorbing films the thickness can be eliminated, and an algebraic equation for e results. This equation is reduced to a quadratic equation. The thickness is then analytically determined also. The effect of measurement errors on the deduced dielectric constant and layer thickness is discussed. Inversion of thin-film data is also considered.