COMPARISON ON THE EFFECT OF SrRuO3 AND La0.5Sr0.5CoO3 BOTTOM ELECTRODE ON DIELECTRIC PROPERTIES OF Ba0.6Sr0.4TiO3 THIN FILMS PREPARED BY PULSED LASER DEPOSITION

摘要

The dielectric properties of Ba0.6Sr0.4TiO3 (BST) thin films deposited using SrRuO3 (SRO) materials as bottom electrode were compared with those of the films grown using La0.5Sr0.5CoO3 (LSCO) materials as bottom electrode. X-ray diffraction scanning revealed that the two kinds of films could be epitaxially grown in pure single-oriented perovskite phases and atomic force microscopy showed that the root mean square roughness of BST/SRO films were similar to BST/LSCO films. The dielectric properties of the BST/SRO and BST/LSCO thin films were measured at 10 kHz and 300 K with a parallel-plate capacitor configuration. Compared with BST/LSCO, the dielectric tunability for BST/SRO films slightly decreased, while the loss decreased synchronously. The figure of merit factor value increases from 25.67 for BST/ LSCO films to 48.76 for BST/SRO films under an applied voltage of 6 V. The leakage current density of the thin films at a positive voltage of 2 V decreases from 2.41 x 10(-7) A/cm(2) for BST/LSCO to 8.41 x 10(-8) A/cm(2) for BST/SRO. This phenomenon is ascribed to the smaller strain induced in BST/SRO materials.