Fabrication of Barium Titanate/Strontium Titanate Artificial Superlattice by Atomic Layer Epitaxy

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Abstract
Epitaxial growth of BaTiO3, SrTiO3 and their superlattices was carried out by the alternating evaporation method using an atomic-layer-epitaxy control system for molecular beam epitaxy (MBE). Stable and reproducible control of the chemical composition was achieved by layer-by-layer growth with this system. Both BaTiO3 and SrTiO3 were grown epitaxially on SrTiO3 substrates, and clear oscillations of reflection high-energy electron diffraction (RHEED) intensity were observed, corresponding to the alternating depositions of BaO and TiO2 in BaTiO3 growth. The artificial superlattice with the structure of [(BaTiO3)5/(SrTiO3)5]7 was fabricated, and the X-ray diffraction (XRD) pattern of the superlattice was simulated by a step model. Diffraction angles of satellite peaks and the shape of Laue peaks in XRD patterns were consistent with those calculated, indicating that the designed structure was fabricated in the superlattice.