Effects of Different Annealing Technique on the Ferroelectric and Leakage Properties of 0.7BiFeO3―0.3PbTiO3 Thin Films

0.7BiFeO3―0.3PbTiO3 (BFPT7030) thin films were prepared on LaNiO3/SiO2/Si substrates by Sol―Gel process. The films were annealed by rapid thermal annealing technique (RTA) and conventional thermal annealing (CTA) technique, respectively. XRD patterns of the films indicate that BFPT7030 films annealed by RTA show a single perovskite phase and better crystallinity as suggested by stronger and sharper XRD peaks. SEM observations demonstrate that BFPT7030 films annealed by RTA are fully crystallized, but films annealed by CTA have a dense morphology and exhibits small grain size especially for film heated at rate of 2 in. Enhanced ferroelectric properties are observed in the films annealed by RTA. The film heated at rate of 20 exhibits a remnant polarization of 22 μC/cm2 with a low coercive field of 70 kV/cm. And lower leakage current density is observed in BFPT7030 films annealed by RTA as compared to BFPT7030 films annealed by CTA. XPS analyses demonstrate that the oxidation state of Fe ions is the coexistence of both Fe3+ and Fe2+ in the BFPT7030 films annealed by RTA and CTA, but less fluctuation of Fe3+ to Fe2+ exists in the BFPT7030 films annealed by CTA.