ELECTRODE INFLUENCE ON THE POLARIZATION PROPERTIES OF BATIO3 THIN FILMS PREPARED BY OFF-AXIS LASER DEPOSITION

摘要

YBa2Cu3O7-x/BaTiO3/YBa2Cu3O7-x and Pt/BaTiO3/Au thin-film capacitors have been grown on SrTiO3(001) and MgO(001) substrates by off-axis laser deposition. Reflection high-energy electron diffraction (RHEED) and pole figures have revealed the epitaxial growth of the YBa2Cu3O7-x and BaTiO3 thin films. The BaTiO3 films with metal electrodes show only weak ferroelectric properties. Using YBa2Cu3O7-x as electrode material an essential improvement of the polarization behaviour could be achieved. YBa2Cu3O7-x/BaTiO3/YBa2Cu3O7-x heterostructures show a typical ferroelectric hysteresis loop with a remanent polarization P-r of 5 mu C cm(-2) and a coercive field E(c) of about 55 kV cm(-1) but with a relatively high leakage current density of about 1 mu A cm(-2) at an applied electrical field of 2 x 10(5) V m(-1). The improved polarization behaviour and the higher leakage current density of the all-perovskite structure is compared to those of the Pt/BaTiO3/Au system. The differences are discussed on the basis of a Schottky-like depletion layer formation at the BaTiO3-electrode interface. [References: 26]