Direct comparison of structural and electrical properties of epitaxial (001)-, (116)-, and (103)-oriented SrBi₂Ta₂O₉ thin films on SrTiO₃ and silicon substrates

Anisotropies of the properties of the bismuth-layered perovskite SrBi₂Ta₂O₉ (SBT) have been investigated using epitaxial thin films grown by pulsed laser deposition both on conducting Nb-doped SrTiO₃ (STO) single crystal substrates and on Si(100) substrates. It has been found that the three-dimensional epitaxy relationship SBT(001)||STO(001); SBT[11̄0]||STO[100] can be applied to all SBT thin films on STO substrates of (001), (011), and (111) orientations. An about 1.7 times larger remanent polarization was obtained in (103)-oriented SBT films than in that of (116) orientation, while the (001)-oriented SBT films revealed no ferroelectricity along their c-axis. Non-c-axis-oriented SBT films with a well-defined (116) orientation were also grown on silicon substrates for the first time. They were deposited on Si(100) covered with a conducting SrRuO₃ (110) bottom electrode on a YSZ(100) buffer layer.