Observation of the Berreman effect in infrared reflection-absorption spectra of amorphous titanium oxide thin films deposited on aluminum

Infrared reflection-absorption spectra of plasma-enhanced chemical vapor de position (PECVD) amorphous TiO2 thin films on aluminum were obtained with s - and p-polarized light and oblique incidence angles. such spectra were ana lyzed by means of spectral simulations based on a Fresnel equation for a th ree-layered system. The optical constants used in the simulations were obta ined through the Kramers-Kronig analysis of the reflectance spectra of a pe llet of powdered amorphous TiO2. LO-TO energy-loss functions were also calc ulated from these optical constants, and a splitting was observed. A good q ualitative agreement between experimental and simulated spectra was achieve d, and the Berreman effect was observed in both cases when p-polarized ligh t was used, It was shown, therefore, that the Berreman effect makes infrare d reflection-absorption spectroscopy a successful technique for the charact erization of an amorphous TiO2 thin layer on aluminum.