Strain and Grain Size Effects on Epitaxial PZT Thin Films

Abstract

AbstractEpitaxial ferroelectric thin films of lead zirconium-titanium oxide, Pb(Zr0.53Ti0.47)O3 (PZT), were successfully grown on SrTiO3, LaAlO3, and Sr(Nb)TiO3 single crystal substrates by a modified RF sputtering technique at high oxygen pressures. The structural properties of the films were evaluated by θ/2θ, ω and ø scans. From these data the crystalline orientation relationships may be extracted. For films grown on SrTiO3 and Sr(Nb)TiO3 substrates, the following orientation relationships were determined: PZT [001] parallel to [001] of the substrate, and PZT [100] parallel to [100] of the substrate. Films grown on LaAlO3 substrates showed a bi-domain crystalline structure with orientation relationships as follows: PZT [100] parallel to [001] of the substrate and PZT [001] parallel to [001] of the substrate. This work was focused to the determination the strain and grain size coefficients, and the analysis of their contribution on the peak broadening in the XRD patterns, and in considering their effects over the ferroelectric behavior. From Williamson-Hall plots, it was possible to conclude that the enhancement of the crystalline film properties (epitaxy and single crystalline domains) reduce the short range strains contribution to peak broadening. On other hand, the grain size contribution to peak broadening was increased with the enhancement of the film cristallinity.