Patterning-controlled morphology of spatially and dimensionally constrained oxide nanostructures

This letter reports a facile approach for morphologic control of complex oxide nanostructures patterned by “soft” electron beam lithography (soft-eBL). The authors demonstrate fabrication of epitaxial nanofrustum and nanopyramidal morphologies of ferroelectric BaTiO3 and magnetic CoFe2O4 lines, with controlled zig-zag or smooth edges. The dimensional and shape control is achieved by simply tuning the patterning parameters such as resist thickness and patterning directions with respect to underlying substrate orientation. The crystal orientation, element distribution, and piezoelectric behavior of BaTiO3 nanofrustums are evaluated with analytical transmission electron microscopy and piezoresponse force microscopy. It is argued that soft-eBL allows for exquisite control over morphology, shape evolution, and orientation of zero- and one-dimensional nanostructures akin to what has been possible in the past with semiconductor heterostructures by thin film approaches.