Formation of Bi-based Layered Perovskite Oxide Films by a Laser Ablation Technique

Abstract

Bi-based layered perovskite oxide films ( SrBi₂Ta₂O₉) have been formed on the Nb-SrTiO₃ substrate or Bi₂Sr₂CuO₆ superconducting bottom electrode with c-axis perpendicular to the substrate surface. The dielectric constants of the c-axis oriented SrBi₂Ta₂O₉ films deposited on the Nb-SrTiO₃ substrate are as high as 100 and remain constant at an applied frequency from 10² to 10⁶ Hz. Furthermore, an artificially Bi-based layered perovskite structure can be constructed by the layer-by-layer successive deposition technique. The BaTiO₃ or SrTiO₃ layer is inserted artificially between the double Bi₂O₂ layers. The formation of “artificially constructed ferroelectric films” by a layer-by-layer deposition method will be discussed and an essential approach to elucidate the mechanism of ferroelectricity.