Shaping single crystalline BaTiOnanostructures by focused neon or helium ion milling.

The realization of perovskite oxide nanostructures with controlled shape and dimensions remains a challenge. Here, we investigate the use of helium and neon focused ion beam (FIB) milling in an ion microscope to fabricate BaTiOnanopillars of sub-500 nm in diameter starting from BaTiO(001) single crystals. Irradiation of BaTiOwith He ions induces the formation of nanobubbles inside the material, eventually leading to surface swelling and blistering. Ne-FIB is shown to be suitable for milling without inducing surface swelling. The resulting structures are defect-free single crystal nanopillars, which are enveloped, on the top and lateral sidewalls, by a point defect-rich crystalline region and an outer Ne-rich amorphous layer. The amorphous layer can be selectively etched by dipping in diluted HF. The geometry and beam-induced damage of the milled nanopillars depend strongly on the patterning parameters and can be well controlled. Ne ion milling is shown to be an effective method to rapidly prototype BaTiOcrystalline nanostructures.