Substrate effect on in-plane ferroelectric and dielectric properties of Ba0.7Sr0.3TiO3 thin films

Abstract

Heteroepitaxial Ba 0.7 Sr 0.3 TiO 3 thin films were grown on (LaAlO 3 ) 0.3 (Sr 2 AlTaO 6 ) 0.35 (001) (LSAT) and SrTiO 3 (001) (STO) single crystal substrates using pulsed laser deposition (PLD). X-ray diffraction characterization revealed a good crystallinity and a pure perovskite structure for films grown on both LSAT and STO substrates. The in-plane ferroelectric and dielectric properties of the films were studied using interdigital electrodes (IDE). The film grown on LSAT substrate exhibited an enhanced in-plane ferroelectricity, including a well-defined P-E hysteresis loop with the remnant polarization P r = 10.5 μC/cm 2 and a butterfly-shaped C-V curve. Nevertheless, only a slim hysteresis loop was observed in the film grown on STO substrate. Curie temperature T c of the film grown on LSAT substrate was found to be ∼105°C, which is nearly 70°C higher than that of the bulk Bao 0.7 Sr 0.3 TiO 3 ceramics. T c of the film grown on STO substrate has almost no change compared to the bulk Ba 0.7 Sr 0.3 TiO 3 ceramics. The dielectric tunabilities were found to be 64% and 52% at 1 MHz for the films grown on LSAT and STO substrates, respectively.