Polarized Raman scattering of highly [111]-oriented Pb(Zr,Ti)O-3 thin films in the rhombohedral-phase field

Abstract

Highly [111]-oriented rhombohedral lead zirconate titanate [Pb(Zr1-xTix)O-3; PZT] thin films were prepared on Pt(111)/Ti/SiO2/Si substrates by suitably combining pulsed laser deposition with sol-gel coating. Two distinctive types of the backscattering geometry were employed for the polarized Raman scattering study: (i) normal backscattering in which the propagation direction of relevant phonons is parallel to the principal [111] polar axis of the rhombohedral 3m (C-3v) point group for observing E(TO) phonons, and (ii) side-view backscattering in which the phonon-propagation direction is normal to the [111] direction for isolating A(1)(TO) phonons. Room-temperature Raman spectra of the [111]-oriented PZT 60/40 film (with Zr/Ti=60/40) having the high-temperature rhombohedral form were examined and compared with those of the [111]-oriented low-temperature rhombohedral PZT 90/10 film which is characterized by the tilting of oxygen octahedra about the principal [111] direction. Similarities and differences in the observed Raman spectra between these two distinctive films were examined in the light of the Raman selection rules for R3m and R3c space groups. (C) 2004 American Institute of Physics.