Nanostructure patterns of piezoelectric and ferroelectric complex oxides with various shapes, obtained by natural lithography and pulsed laser deposition

A variety of patterns of well-ordered perovskite-type complex oxide nanostructures were obtained by pulsed laser deposition (PLD) on conductive single crystalline substrates through latex sphere monolayer and double-layer masks. Patterns obtained via deposition through hexagonally close packed (hcp) latex sphere monolayers include the usual arrays of hexagonally ordered nanoislands, hexagonal arrays of nanorings of much lower height coexisting with hexagonal nanoislands, hcp shell-like structures, and hexagonally interconnected nanocrown arrays. The formation of the nanopatterns depends on the ambient gas pressure during PLD, with well-separated nanoislands obtained at low pressures, and interconnected nanocrowns formed at high pressures. After annealing, the obtained BaTiO3 and SrBi2Ta2O9 nanopatterns were examined by piezoresponse force microscopy using conductive scanning probes. Under an external biasing electric field, polarization domain reversal was observed in the nanopatterns with deep submicron lateral dimensions. BaTiO3 nanocrowns similar to 9 nm high are ferroelectric, while SrBi2Ta2O9 nanorings of similar to 5 nm thickness show at least piezoelectric activity. In addition to the patterns of hexagonally ordered nanostructure arrays, a pattern of rhombohedrally ordered nanostructure arrays was also fabricated by deposition through latex sphere double layers.