GROWTH OF ULTRATHIN BATIO3 FILMS ON SRTIO3 AND MGO SUBSTRATES

Epitaxial BaTiO3 thin films were successfully grown on SrTiO3 (001) an d MgO (001) substrates by molecular beam epitaxy. These 50 ML thicknes s BaTiO3 films were prepared under the same growth conditions on both substrates. The films were characterized by in situ reflection high-en ergy-electron diffraction observations and ex situ X-ray diffraction m easurements. The epitaxial relationship between the BaTiO3 films and b oth substrates was cube-on-cube, though the cubic lattice parameter of BaTiO3 was larger than that of SrTiO3, and smaller than that of MgO a t the growth temperature (700 degrees C). In addition, the films on bo th substrates were found to have a highly c-axis-oriented tetragonal p hase at room temperature. However, despite the finding that the lattic e parameters of these films were very close to the bulk value of the t etragonal phase, the crystal quality as found to depend strongly on th e magnitude of the lattice mismatch. (C) 1998 Elsevier Science B.V. Al l rights reserved.