Growth of Pyrochlore Bi₂Ti₂O₇ Epitaxial Films and Their Electrical Characterization

Abstract

Epitaxial growth condition of Bi₂Ti₂O₇ films on the substrates having rutile-structure was investigated. TiO₂ single crystals and the conductive epitaxial IrO₂layers having same rutile-structure were used as substrates for film deposition. Strongly (111)-oriented Bi₂Ti₂O₇ films were confirmed to be deposited on (110) TiO₂ substrates by XRD θ-2θ scans, but obvious orientations were not detected on (100), (001) and (110) TiO₂ substrates. The epitaxial growths of Bi₂Ti₂O₇ films were confirmed on (100), (001) and (110) TiO₂ substrates, where two variants were observed on (100) and (110) TiO₂ substrates. The epitaxial relationships were confirmed as follows; (14 14 19)Bi₂Ti₂O₇//(100)TiO₂, (112)Bi₂Ti₂O₇//(101)TiO₂, and (111)Bi₂Ti₂O₇//(110)TiO₂. Same epitaxial growth was confirmed only on (110)IrO₂//(110)TiO₂ substrate, but not on (101)IrO₂//(012)Al₂O₃ and (100)IrO₂//(100)TiO₂ substrates. The dielectric constant and loss tangent at 1 kHz were 130 and 2%, respectively for the 130 nm-thick epitaxial Bi₂Ti₂O₇ film grown on (110)IrO₂//(110)TiO₂ substrate.

Keywords:

• pyrochlore
• epitaxial growth
• MOCVD