Vertically aligned 1D ZnO nanostructures on bulk alloy substrates: Direct solution synthesis, photoluminescence, and field emission

We report a highly effective growth of vertically aligned ZnO one-dimensional (1D) nanostructures on conducting alloy substrate (Fe-Co-Ni) in mild solutions (T <= 70 degrees C) in the absence of any seeds, catalysts, and surfactants. The growth conditions such as NH3 center dot H2O concentration, temperature, and nature of the substrate are correlated to affect the nanostructure formation. Different ZnO single-crystal nanostructures including nanoneedles, hexagonal nanorods, and nanopencils oriented normal to the substrate can be selectively formed in high quantity. The ordered ZnO nanostructures show strong UV excitonic emissions and good field emission (FE) properties. Other metal substrates such as Ti and Ni are also proven to be effective for ZnO nanoarray growth. Since metal substrates are much more economical and scalable than Si, sapphire/Al2O3, GaN, etc., we believe that our approach presents a general economical route toward mass production of controllable ZnO arrays and will facilitate flexible design of device architectures for nanoelectronics.