Atomic Layr Epitaxy and Property of Artificial Superlattice with Perovskite Type Structure

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In the present study, we have developed a fabrication process of BaTiO_3-SrTiO_3 artificial superlattices with Perovskite type structure by molecular beam epitaxy, and analyzed the crystal structure of the superlattices. We have also measured dielectric property of the superlattices. Results of the research are summarized as follows.1) BaTiO_3-SrTiO_3 superlattices could be fabricated by atomic layr epitaxy where constituent elements were deposited atomic layr-by-layr using a molecular beam epitaxy technique.2) Crystal structure analysis method of artificial superlattice was developed. A software which calculates X-ray diffraction pattern of an artificial superlattice with arbitrary structure was developed and used for structure analysis. It was found calculation and experimental results agreed well by taking into account thermal diffusion of Ba and Sr atoms at interface layr between BaTiO_3 and SrTiO_3.3) In order to prevent the thermal diffusion of constituent elements, a low temperature epitaxy of BaTiO_3 on SiTiO_3 substrates was tried. It was found that epitaxial growth was achieved at 400ﾟC by irradiating low energy oxygen ion beam.4) Dielectric property of the artificial superlattice deposited on a conductive SrTiO_3 substrates was measured. Dielectric property was markedly changed with the structure of the superlattices even if the total thickness and chemical composition of the superlattices were identical.