BaTiO3 thin films grown on SrTiO3 substrates by a molecular-beam-epitaxy method using oxygen radicals

Abstract

BaTiO3 (BT) thin films were grown by a molecular-beam-epitaxy method using an oxygen radical source. BaO and TiO2 layers were alternately deposited on SrTiO3 (001) (ST) substrates, and the structure of the thin films obtained was evaluated by x-ray diffraction, reflection high-energy electron diffraction, transmission electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy. The BT thin films were oriented in the [001] direction and epitaxially grown without misfit dislocations. The lattice constants of the thin films varied with distance from the interface of BT and ST. Near the interface the a value was shorter than that for bulk BT while the c value was longer than that for bulk BT. The surface analysis indicated that adsorbed oxygen was enriched on the BaO-terminated surface in comparison with the TiO2-terminated surface.