Ultraviolet-emitting ZnO nanowhiskers prepared by a vapor transport process on prestructured surfaces with self-assembled polymers

Abstract

ZnO wires were grown by a vapor–liquid–solid phase transport process. Self-assembled Au nano-clusters act as a catalyst or seed for the highly oriented growth of so-called ZnO whiskers on sapphire substrates by a vapor–liquid–solid phase transport process. The ZnO nanowires were more than 500 nm high and smaller than 30 nm in diameter. Low-temperature photoluminescence measurements reveal intense and detailed ultraviolet light emission near the opitical band gap of ZnO at 3.37 eV. The ZnO nanowires show almost no broad green photoluminescence emission band related to oxygen defects and only a weak signal due to donor–acceptor pair recombination. X-ray diffraction proves that the ZnO wires were grown c-plane oriented on an a-plane sapphire substrate with high crystal quality most likely because of a kind of self-purification during the growth process.