Polarized Raman scattering of epitaxial Pb(Zr,Ti)O3 thin films in the tetragonal-phase field

In view of the difficulty in preparing single crystals, a c-axis oriented epitaxial lead zirconate titanate (PZT) film was prepared as a model system for the single-crystalline PZT. By employing an extraordinary backscattering configuration in which the relevant phonon wave vector, k, is parallel to the film/substrate interface, we have successfully isolated the E [transverse optical (TO)] symmetry phonons from A1(TO) phonons. Compared with polarized Raman spectra of the c-axis oriented PbTiO3 film, the polarized spectra of the epitaxial PZT film (with Zr/Ti=40/60) exhibited significant asymmetric line broadening with a noticeable downward shift of the mode frequencies. In addition to this, we observed a splitting of the “silent” mode into the B1-symmetry mode and the E(TO) mode using the parallel and cross polarization configurations, respectively.