Regular ZnO nanopillar arrays by nanosphere photolithography

Highly regular vertical ZnO nanopillar arrays were hydrothermally grown through a nucleation window pattern generated by nanosphere photolithography. The in-plane intensity modulation of the exposing ultraviolet light in the photoresist was performed by Stöber silica or polystyrene nanospheres in the masking Langmuir–Blodgett monolayer. By comparing six different nanosphere diameters in the 180–700 nm range only those with diameter above the exposure wavelength of 405 nm generate a pattern in the thin photoresist layer. The pattern quality is improving with increasing diameter, therefore, the masking for nanopillar growth was demonstrated with 700 nm polystyrene nanospheres. The results of the nanosphere photolithography were supported by finite-difference time-domain calculations. This growth approach was shown to have the potential for low-cost, low-temperature, large area fabrication of ZnO pillars or nanowires enabling a precise engineering of geometry.

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► Highly ordered ZnO nanopillar arrays were grown using nanosphere photolithography.
► The nanosphere photolithography was optimized both theoretically and experimentally.
► The diameter of the nanospheres has to be larger than the exposing light wavelength.
► The nanostructure is determined by the seed layer and by the mask pattern.