Phase stability of heteroepitaxial polydomain BaTiO₃ thin films

Abstract

The phase stability of ferroelectric, epitaxial, polydomain BaTiO 3 thin films was examined using temperature-dependent x-ray diffraction (XRD) and in-plane electronic polarization measurements. The epitaxial BaTiO 3 thin films were grown on MgO(100) substrates by a metal-organic chemical vapor deposition process. As-deposited and annealed BaTiO 3 thin films with different domain structures were examined. Temperature-dependent plane-normal XRD analysis reveals well-defined phase transitions at 140 and 169°C in the c-and a-oriented films, respectively. The measured Curie temperatures are consistent with those predicted by Landau-Ginsburg-Devonshire theory as applied to polydomain BaTiO 3 thin films. Temperature-dependent in-plane electronic polarization measurements confirm that the 140°C Curie temperature observed in the c-oriented film is a well-defined second-order paraelectric-ferroelectric transition.

Enhanced resistive switching characteristics in Pt/BaTiO3/ITO structures through insertion of HfO2:Al2O3 (HAO) dielectric thin layer

“…The increase of T c is due to the presence of tensile stress36, owing to the thermal expansion coefficient difference between film and substrate, as it is evidenced by XRD analysis. The moderate increase in transition temperatures is consistent with the Landau-Ginsburg-Devonshire theory for polydomain thin films with residual misfit strain less than 0.2%37. In our case, the increase of T c is predominantly due to the thermal tensile strain, which was calculated from the XRD analysis and is equal to 0.3%.…”