Electrical behaviors of c-axis textured 0.975Bi0.5Na0.5TiO3–0.025BiCoO3 thin films grown by pulsed laser deposition

Abstract

The thin films of 0.975Bi0.5Na0.5TiO3–0.025BiCoO3 (BNT-BC) have been successfully deposited on (111) Pt/Ti/SiO2/Si (100) substrates by pulse laser deposition and their ferroelectric, dielectric, local piezoelectric properties and temperature dependent leakage current behaviors have been investigated systematically. X-ray diffraction indicates the films are single phased and c-axis oriented. The thin films exhibit ferroelectric polarization–electric field (P–E) hysteresis loop with a remnant polarization (Pr) of 10.0μC/cm2 and an excellent fatigue resistance property up to 5×109 switching cycles. The dielectric constant and dielectric loss are 500 and 0.22at 1kHz, respectively. The tunability of the dielectric constant is about 12% at 20kV/mm. The piezo-phase response hysteresis loop and piezo-amplitude response butterfly curve are observed by switching spectroscopy mode of piezoelectric force microscope (SS-PFM) and the piezoelectric coefficient d33 is about 19–63pm/V, which is comparable to other reports. The dominant leakage current conduction mechanisms are ohmic conduction at low electric field and Schottky emission at high electric field, respectively. Our results may be helpful for further work on BNT-based thin films with improved electric properties.