Microstructure dependence of the electrical properties of (Ba,Sr)TiO3 thin film deposited on (La,Sr)MnO3 conductive layer

(0 0 l)-oriented Ba0.7Sr0.3TiO3 (BST)/La0.67Sr0.33MnO3 (LSMO) heterostructures were deposited on (0 0 1) LaAlO3 substrates by pulsed laser deposition. We found that both the crystallinity and grain size of the BST films increased with increasing deposition temperature from 550 to 850 °C. The ferroelectric properties of the BST/LSMO heterostructures were also enhanced by increasing the deposition temperature, while the largest remnant polarization and saturation polarization were 2.6 and 9.1 μC/cm2, respectively. Correspondingly, the dielectric constant (zero bias) increased from 592 to 852 and the dielectric tunability (220 kV/cm) increased from 9.61 to 39.3%, which may be attributed to the better crystallinity and larger grain size of the BST films. As for the current-voltage characteristics of the BST/LSMO heterostructures, the leakage current was higher for the larger grain sizes. Further study on the leakage current induced by grain size was carried out as well.