Epitaxial growth and electrical properties of Ba0.6Sr0.4TiO3 thin films with conductive La0.5Sr0.5CoO3 bottom electrodes

Abstract

Epitaxial Ba0.6Sr0.4TiO3 (BST) thin films were deposited on LaAlO3 (LAO) substrates with the conductive metallic oxide La0.5Sr0.5CoO3 (LSCO) film as a bottom electrode by pulsed laser deposition (PLD). X-ray diffraction θ~2θ and Φ scan showed that the epitaxial relationship of BST /LSCO /LAO was [001] BST//[001] LSCO//[001] LAO. The atomic force microscope (AFM) revealed a smooth and crack-free surface of BST films on LSCO-coated LAO substrate with the average grain size of 120 nm and the RMS of 1.564nm for BST films. Pt/BST/LSCO capacitor was fabricated to perform Capacitance-Voltage measurement indicating good insulating characteristics. For epitaxial BST film, the dielectric constant and dielectric loss were determined as 471 and 0.03, respectively. The tunabilty was 79.59% and the leakage current was 2.63×10-7 A/cm2 under an applied filed of 200 kV/cm.