Infrared ellipsometric study on PZT thin films

We measured the pseudo-dielectric functions in the far infrared spectral range between 250 cm(-1) and 1200 cm(-1) of Pb(ZrxTi1-x)O-3 (x = 0.2, 0.56, and 0.82), Pb0.98Nb0.04(Zr0.2Ti0.8)(0.96)O-3, Pb0.91La0.09(Zr0.65Ti0.35)(0.98)O-3, and Pb0.85La0.15Ti0.96O3 grown on platinized silicon substrates by using the sol-gel method and grown on (0001) sapphire by using radio-frequency sputtering deposition. Using a factorized form of the dielectric phonon response, we estimated the dielectric functions and the phonon mode frequencies of the ferroelectric thin films. We assumed that the dielectric functions of the films were optically isotropic because of their polycrystalline properties. The lattice properties of the PZT films, such as phonon frequencies and broadening parameters, were studied as functions of the Zr content. Our study provides detailed information on the infrared dielectric functions and the phonon frequencies of PZT-related ferroelectric thin films.