MOCVD growth of epitaxial pyrochlore Bi₂Ti₂ O₇ thin film

Growth of Bi₂Ti₂O₇ films on the substrates having cubic-structure was investigated by metal organic chemical vapor deposition (MOCVD). (1 0 0), (1 1 0) and (1 1 1)SrTiO₃ single crystals, (1 1 1)-oriented Pt- and SrRuO₃-coated (1 1 1)SrTiO₃ were used as substrates together with (1 1 1)Pt/TiO₂/SiO₂/Si. Peaks originated to Bi₂Ti₂O₇ phase were not detected on (1 0 0), (1 1 0) and (1 1 1)SrTiO₃ substrates. On the other hand, (1 1 1)-oriented Bi₂ Ti₂O₇ phase was ascertained to be prepared on (1 1 1)Pt//(1 1 1)SrTiO₃ and (1 1 1)Pt/TiO₂/ SiO₂/Si substrates in spite of the almost the same lattice parameters of SrRuO₃ and SrTiO₃ with Pt. From the pole figure measurement, Bi₂Ti₂O₇ films prepared on the (1 1 1)Pt//(1 1 1)SrTiO₃ substrates were ascertained epitaxial grown, (1 1 1)Bi₂Ti₂ O₇//(1 1 1)Pt//(1 1 1)SrTiO₃, while that on the (1 1 1)Pt/TiO₂/SiO₂/Si were (1 1 1)-one-axis-oriented Bi₂Ti₂O₇ with in-plain random. The easy growth of (1 1 1)-oriented Bi₂Ti₂O₇ film on (1 1 1)Pt layer can be explain by the existence of the sub-unit in (1 1 1)Pt plane consist of three Pt atoms.