BARIUM TITANATE FILMS FOR ELECTRONIC APPLICATIONS: STRUCTURAL AND DIELECTRIC PROPERTIES

Abstract

Synthesis of the precursors, using research grade materials and locally available facilities, is optimized in order to obtain a suitable sol for BaTiO 3. The optimally synthesized BaTiO 3 sol is then spun onto Cu substrates to obtain films of thickness ~0.5 μm. The deposited BaTiO 3 films are heated up to a temperature of 300°C. Surface and structural changes, with heating, are observed by optical microscope, scanning electron microscope, atomic force microscope, and X-ray diffraction. The surface cracked in some cases but is generally uniform, as seen with SEM and AFM, in case of optimized conditions. The SEM images reveal large crystallites, which are correlated to the XRD observation of tetragonal perovskite structure of these sol–gel films. The AFM scan, however, shows an rms roughness of 35.6 nm for an area of 3 μm × 3 μm. Tetragonal perovskite BaTiO 3 is obtained at a temperature of as low as 300°C. The dielectric constant and loss angle, in the 30 Hz–3 MHz range, are calculated at room temperature and up to 200°C. At high frequencies the dielectric constant (~290) and loss angle (~2 × 10-6) values indicate the usefulness of such films in electronic applications. The leakage current is also measured at room temperature and a conductivity of 2.0 × 10-15 S/cm is obtained.