MOCVD growth of epitaxial pyrochlore Bi2Ti2O7 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 Bi2Ti2O7 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)Bi2Ti2O7//(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.