Microstructure and electrical properties of Mn-doped barium strontium titanate thin films prepared on copper foils

Ba(0.7-x)Sr(0.3)Mn(x)TiO(3) (x = 0, 0.025, 0.05) thin films have been prepared on copper foils using sol-gel method. The films were processed in an atmosphere with low oxygen pressure so that the substrate oxidation is avoided and the formation of the perovskite phase is allowed. XRD and SEM results showed that Mn doping enhanced the crystallization of the perovskite phase in the films. TheMnsubstitution prevents the reduction of Ti(4+) to Ti(3+), which is supported by XPS analysis. The Ba(0.7-x)Sr(0.3)Mn(x)TiO(3) film with x = 0.025 (BSMT25) exhibits preferred dielectric behavior and a lower leakage current density among the three thin films. The dielectric constant and loss of the BSMT25 film are 1213.5 and 0.065 at 1MHz and around zero field, which are mostly desired for embedded capacitor applications. The mechanism of Mn doping on improving the electrical properties of barium strontium titanate (BST) thin films was investigated. (C) 2010 Elsevier B.V. All rights reserved.