Ferroelectric nanostructures via a modified focused ion beam technique

In this paper we demonstrate a modified focused ion beam (FIB) milling approach integrated with self-alignment to synthesize ferroelectric nanostructures. Nanoscale holes ranging from 500 nm down to 100 nm in diameter are created on 'spun-on' amorphous TiO2 on Pt/TiO2/Si using FIB milling. It is found that spin-coating of PbZr0.4Ti 0.6O3 (PZT) sol-gel precursors on these templated surfaces followed by low-temperature (∼400 °C) annealing leads to a ferroelectric phase only within the holes. Piezoresponse force microscopy (PFM) was used to confirm that the crystallized phase within the holes were ferroelectric and switchable. The smallest lateral size shown to be ferroelectric is roughly 70-80 nm in diameter. Quantitative PFM of the nanoscale ferroelectric regions yielded a value of 17 pm V-1, in good agreement with previously published data on polycrystalline PZT. Additionally this method facilitates the integration of interlayer dielectrics or 'spun-on' glass during the synthesis without the need for additional lithography and processing.