Effect of excess bismuth on the microstructures and electrical properties of strontium bismuth tantalate (SBT) thin films

Strontium bismuth tantalate (SBT) films with excess Bi contents were prepared on Pt/TiO2/SiO2/Si substrates by a metallorganic decomposition technique. Effect of excess Bi contents on the microstructure and electrical properties were investigated. A predominant layered perovskite structure could be formed when an excess Bi less than 30% was added. For films above 30% excess of Bi, secondary phases occurred. The remnant polarization and dielectric constant decreased with excess Bi content. This was attributed to a smaller grain size and the presence of secondary phases. The leakage current characteristics were also examined. Space charge limited mechanism was observed in SBT films. In summary, 10% excess Bi was found to be the optimum composition with respect to grain size, morphology, and electrical properties. (C) 2000 Elsevier Science S.A. All rights reserved.