Fabrication of vertically aligned ZnO nanocone arrays by wet chemical etching on various substrates and enhanced photoluminescence emission from nanocone arrays compared to nanowire arrays

We report a systematic and reliable approach to fabricate ZnO nanocone or nanoneedle arrays on various substrates including fibers. Our approach employs wet chemical etching of ZnO nanowire arrays using an aqueous solution of HCl. Using this simple chemical etching technique, nanowire arrays were transformed to nanocone arrays on Si substrates and Kevlar fibers. Significant enhancement of light emission intensities at UV peak (∼387 nm) was observed when the ZnO nanowire arrays are converted to ZnO nanocone arrays. The photoluminescence intensities at the UV peaks from the nanocones are found to be ∼3–4 times larger than those from the nanowires.