K. Kaemmer et al., ELECTRODE INFLUENCE ON THE POLARIZATION PROPERTIES OF BATIO3 THIN-FILMS PREPARED BY OFF-AXIS LASER DEPOSITION, Journal of physics. D, Applied physics, 30(4), 1997, pp. 522-526
YBa2Cu3O7-x/BaTiO3/YBa2Cu3O7-x and Pt/BaTiO3/Au thin-film capacitors h
ave been grown on SrTiO3(001) and MgO(001) substrates by off-axis lase
r 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 w
eak ferroelectric properties. Using YBa2Cu3O7-x as electrode material
an essential improvement of the polarization behaviour could be achiev
ed. YBa2Cu3O7-x/BaTiO3/YBa2Cu3O7-x heterostructures show a typical fer
roelectric 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 rela
tively high leakage current density of about 1 mu A cm(-2) at an appli
ed electrical field of 2 x 10(5) V m(-1). The improved polarization be
haviour and the higher leakage current density of the all-perovskite s
tructure is compared to those of the Pt/BaTiO3/Au system. The differen
ces are discussed on the basis of a Schottky-like depletion layer form
ation at the BaTiO3-electrode interface.