Berreman effect applied to phase characterization of thin films supported on metallic substrates: The case ofTiO2

摘要: Infrared reflection-absorption spectra of ${\mathrm{TiO}}_{2}$ thin films deposited by plasma-enhanced chemical vapor deposition onto aluminum and a sol-gel process platinum were obtained using s- p-polarized light oblique incidence angles. Prominent bands with variable reflection minima position line shapes, which shown to be phase dependent, observed for all samples in the $800\ensuremath{-}900 {\mathrm{cm}}^{\ensuremath{-}1}$ wave number range when used. Such attributed an LO mode their enhancement angle is good example Berreman effect. analyzed means spectral simulation based on Fresnel equation three-layered system. The films' optical constants used simulations through Kramers-Kr\"onig analysis (KKA) reflectance pellets powdered amorphous ${\mathrm{TiO}}_{2},$ anatase rutile. Optical hypothetical polycrystalline systems also calculated from dielectric functions single crystals effective medium theories (EMTs), such as those Bruggeman, Maxwell-Garnett, Hunderi. These both understanding observed. However, standards determined KKA reproduced experimental results more accurately than EMTs. In simulated spectra, effect was very clear-cut reliable characterization could carried out.