CRYSTALLOGRAPHIC AND MICROSTRUCTURAL STUDIES OF BATIO3 THIN-FILMS GROWN ON SRTIO3 BY LASER MOLECULAR-BEAM EPITAXY

A series of trial tests were carried out to grow BaTiO3 thin films on SrTiO3 substrates in our newly built laser molecular beam epitaxial sy stem. The phase, crystallographic orientation and crystalline quality of the films were investigated by x-ray diffraction theta/2 theta scan , symmetric and asymmetric rocking curves (omega scans) and phi scan. The interfacial microstructures of the BaTiO3/SrTiO3 and the surface m orphology of BaTiO3 films were analyzed by cross-section transmission electron microscopy and atomic force microscopy. Under appropriate gro wth conditions, epitaxial, single-crystal films with fully c-axis orie nted tetragonal structure were obtained. The tetragonality was calcula ted by using {303} asymmetric rocking curve for a BaTiO3 thin film to be 1.027, which is larger than the bulk value of BaTiO3. The BaTiO3/Sr TiO3 interface is very abrupt with no transitional layer and the BaTiO 3 film exhibits an atomically smooth surface. (C) 1997 American Vacuum Society.