Crystallographic and Electrical Properties of Epitaxial BaTiO₃ Film Grown on Conductive and Insulating Perovskite Oxides

BaTiO 3 films of various thicknesses were grown on doped and undoped SrTiO 3 (100) substrates and on (La, Sr) 2 CuO 4 films by a pulse laser deposition method. Both BaTiO 3 and (La, Sr) 2 CuO 4 films were smooth and free of particulates. X-ray diffractometry showed that all materials were three-dimensionally aligned with the cube-on-cube epitaxial relationship, and that the films obtained on SrTiO 3 (100) were of a c -axis-oriented tetragonal phase contrary to previous studies using metal bottom electrodes. As the film thickness decreased, the tetragonality of these films increased and the dielectric constant along the c -axis decreased rapidly, despite reduction of disorder at the interface by use of perovskite electrodes. The 2000-Å-thick BaTiO 3 grown on (La, Sr) 2 CuO 4 film had the remnant polarization of about 1.5 µ C/cm 2 . The results were discussed using a surface layer model.