Interpretation of in-plane and out-of-plane anisotropic surface–interface reflectance and transmittance difference spectroscopy

A numerical method developed previously [J. Appl. Phys.80, 4621 (1996)] has been extended to simulate the nonnormal-incidence reflectance-difference spectroscopy and transmittance-difference spectroscopy spectra of biaxial anisotropic (∊x≠∊y≠∊z) multilayer systems with finite thickness. It is demonstrated that, when the principal axes of the anisotropy layer are at certain orientations, a reflectance-difference spectrum can be separated into two spectra, namely, an in-plane anisotropic spectrum and an out-of-plane anisotropic spectrum. It is shown that the separation is valid for large in-plane anisotropy, i.e., |∊x-∊y|≈|∊x|, and an incident angle of ≤20°.