Synthesis and ferroelectric properties of epitaxial BiFeO3 thin films grown by sputtering

We have grown epitaxial BiFeO3 thin films with smooth surfaces on (001), (101), and (111) SrTiO3 substrates using sputtering. Four-circle x-ray diffraction and cross-sectional transmission electron microscopy show that the BiFeO3 thin films have rhombohedral symmetry although small monoclinic distortions have not been ruled out. Stripe ferroelectric domains oriented perpendicular to the substrate miscut direction and free of impurity phase are observed in BiFeO3 on high miscut (4°) (001) SrTiO3, which attributes to a relatively high value of remanent polarization (∼71μC∕cm2). Films grown on low miscut (0.8°) SrTiO3 have a small amount of impure phase α-Fe2O3 which contributes to lower the polarization values (∼63μC∕cm2). The BiFeO3 films grown on (101) and (111) SrTiO3 exhibited remanent polarizations of 86 and 98μC∕cm2, respectively.