STRUCTURAL CHARACTERIZATION OF BATIO3 THIN-FILMS GROWN BY MOLECULAR-BEAM EPITAXY

Epitaxial ultrathin films of BaTiO3 were prepared using molecular beam epitaxy. For the substrate, (001)-oriented SrTiO3 single crystals wer e used. Controlling the growth conditions of these films as well as th e semiconductor thin films, led to the successful growth of the BaTiO3 films as single crystals, characterized by x-ray diffraction even in the ultrathin range. The ultrathin BaTiO3 films are highly c-axis-orie nted tetragonal phaselike bulk BaTiO3 crystals. The tetragonality of t he thin film crystals is much larger than bulk crystal's. We also meas ured the saturated polarization (Ps) of the BaTiO3 films at temperatur es ranging from room temperature to 600 degrees C. The results confirm ed again that the films are ferroelectric tetragonal phase crystals. M oreover, they showed that the transition temperature for the ferroelec tric-paraelectric phase transition of the films is higher than bulk cr ystal's. (C) 1998 American Institute of Physics.