Fatigue and ferroelectric behavior of la and Zn comodified BiFeO 3 thin films

Abstract

Bi0.90La0.10Fe0.95Zn0.05O 3 (BLFZO) thin films were grown directly on Pt/TiO 2/SiO2/Si (100) substrates without any buffer layer by off-axis radio frequency sputtering. The BLFZO thin film deposited at 580 °C possesses a single-phase purity, while those deposited at other temperatures exhibit a varying amount of second phases, indicating that the deposition temperature plays a critical role in the phase development of BLFZO thin films. Although La and Zn cosubstitutions lower the Curie temperature (Tc) of BiFeO3 thin films, the resulting Tc value (∼630 °C) is still much higher as compared to other lead-based or lead-free ferroelectric thin films. The BLFZO thin film exhibits a remanent polarization of 2 Pr ∼131.7 μC/cm2 and a coercive field of 2 Ec ∼496 kV/cm, in association with the improvement in electrical resistance. On the basis of the studies for frequency (1 kHz∼1 MHz) and driving field (0.8 Ec ∼2.0 Ec) dependences, the BLFZO thin film demonstrates the desired fatigue endurance and weak frequency and driving field dependence. La and Zn cosubstitutions are shown to contribute toward the high remanent polarization and fatigue endurance. © 2010 American Institute of Physics.