Fast synthesis of ZnO nanostructures by laser-induced chemical liquid deposition

ZnO nanostructures were obtained by directly irradiating a small volume of a solution of precursor on a fused-quartz substrate using an unfocused continuous wave CO₂ laser for 2-30 s at laser powers ranging from 20 to 40 W. The laser-based thermochemistry approach allows rapid non-isothermal heating and convection enhanced mass transport which opens new growth mechanisms for the rapid deposition of nanomaterials at predetermined locations on a substrate. The deposits consist of a variety of ZnO nanostructure morphologies, including aggregated nanoparticles, nanorods, faceted nanocrystals and nanowires. The samples were characterized by scanning and transmission electron microscopy, X-ray diffraction and photoluminescence spectroscopy. They were found to exhibit an intense room-temperature photoluminescence, which is characterized by the presence of a strong UV peak around 390 nm and no visible emission. The relationship between the PL signal characteristics and specific ZnO nanostructures was investigated in order to point up optimal nanostructures for possible luminescent devices.