Crystal structure and electrical properties of epitaxial SrBi2Ta2O9 films

The crystal structure and electrical properties were investigated for (001)- and (116)-oriented SrBi2Ta2O9 (SBT) thin films deposited on (100) SrTiO3 and (100)SrRuO3∥(100)SrTiO3 substrates, and (110) SrTiO3 and (110)SrRuO3∥(110)SrTiO3 substrates, respectively. Both oriented SBT films were epitaxially grown with high crystal perfection, and twinning existed in the (116)-oriented one. Both oriented SBT films were found to form c/6 lattice displacements to relax the stress. The interface of the (001)-oriented film did not include misfit dislocations, defects, and an interfacial layer, and that of the (116)-oriented film included the lattice strain contrast due to an irregular atomic arrangement. The electrical property of the SBT film shows anisotropy of the ferroelectricity along the c- and a-axis directions; the remanent polarizations of the (001)- and (116)-oriented SBT films were 0 and 10.5 μC/cm2, respectively.