Epitaxial BiFeO₃ nanostructures fabricated by differential etching of BiFeO₃ films

We report on differential etching behavior of the different orientations of the polarization in BiFeO₃ (BFO), similar to other ferroelectrics, such as LiNbO₃. We show how this effect can be used to fabricate epitaxial BiFeO₃ nanostructures. By means of piezoresponse force microscopy (PFM) domains of arbitrary shape and size can be poled in an epitaxial BiFeO₃ film, which are then reproduced in the film morphology by differential etching. Structures with a lateral size smaller than 200 nm were fabricated and very good retention properties as well as a highly increased piezoelectric response were detected by PFM.