Characterization of Ferroelectric Property of C-Axis- and Non-C-Axis-Oriented Epitaxially Grown Bi2VO5.5 Thin Films

Epitaxial Bi2VO5.5 films with c-axis- and non-c-axis-orientations were grown by metalorganic chemical vapor deposition. (001)-, (114)- and (102)-oriented Bi2VO5.5 films were epitaxialy grown on (100), (110) and (111)SrTiO3 substrates, respectively. Electrical properties of the (001)- and (114)-oriented films on (100)SrRuO3∥(100)SrTiO3 and (110)SrRuO3∥(110)SrTiO3 substrates were compared. The dielectric constant (ε r) of the (001)-oriented film was smaller than that of the (114)-oriented one, suggesting that ε r along the c-axis is smaller than that along other axes. Leakage current density of the (001)-oriented film was smaller than that of the (114)-oriented one. These results were in good agreement with those of the crystallographically equivalent oriented films of SrBi2Ta2O9 and Bi4Ti3O12. Ferroelectricity and domain structure were observed for both films by Polarization-Electric field measurements and scanning nonlinear dielectric microscopy, respectively. However, the large difference of remanent polarization depending on the film orientation observed for SrBi2Ta2O9 and Bi4Ti3O12 films was not observed for Bi2VO5.5 films.