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 degrees 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 mu C/cm(2), 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. (c) 2004 Elsevier B.V. All rights reserved.