A General Low-Temperature Route for Large-Scale Fabrication of Highly Oriented ZnO Nanorod/Nanotube Arrays

摘要

As a wide band gap semiconductor oxide with a large excitation binding energy (60 meV),zinc oxide becomes one of the most important functional materials with unique properties of near-UV emission,optical transparency,electric conductivity,and piezo electricity.Since the first report of ultraviolet lasing from ZnO nanorods,substantial effort has been devoted to the development of novel synthetic methodologies for one-dimensional (1D) ZnO nanostructures due to their promising applications in electronic and optoelectronic devices.Currently,large-scale low-cost controllable growth of well-aligned ZnO nanorods on properly fitting substrates is crucially expected for these novel applications.As the widely used high-temperature vapor-phase processes are expensive and energy-consuming,various solution-phase approaches to ZnO nanorods have recently attracted extensive interest because of their low growth temperatures (90-95degC) and good potential for scale-up.Among these reported approaches,the most successful one is based on the seeded growth of well-oriented ZnO nanorod arrays on ZnO-nanoparticle-coated substrates.However,the liquid-phase coating of the substrates with ZnO nanoparticles prepared in solution remains complex and difficult/irreproducible.Here,a conventional radio frequency magnetron-sputtering technique was utilized to simply prepare ZnO-film-coated substrates for subsequent growth of highly oriented ZnO nanorods.The highly oriented ZnO nanorods can be easily fabricated on ZnO-film-coated (arbitrary) substrates over a large area via a simple low-temperature solution route.This novel synthetic approach also allows further reducing the growth temperature to 65degC,leading to the development of an effective and low-cost fabrication process for high-quality ZnO nanorod arrays.Moreover,we report the low-temperature synthesis of hexagonal ZnO nanotube arrays,which can be formed on zinc foils in the same reaction system.