Large-Scale Synthesis of Bicrystalline ZnO NanowireArrays by Thermal Oxidation of Zinc Film: Growth Mechanism and High-PerformanceField Emission.

Understanding the origin crystalnucleation and driving force iscritical for the synthesis of one-dimensional nanomaterials with controllablesize, morphology, and crystal structure. The growth behavior of ZnOnanowires prepared by thermal oxidation of zinc film is studied. Itis found that the grown nanowires have a bicrystalline structure andgrowth direction significantly different from the commonly observed[0001] direction. On the basis of detailed high resolution morphologyand structural analysis, we propose the origin of the initial growthsite, as well as the driving force for formation of the bicrystallinestructure of aligned ZnO nanowires. The initial zinc film plays animportant role in the growth of nanowire. The edge-enhanced oxidationeffect of zinc grain initiates the ZnO nanowire nucleation. The strainwithin the ZnO layer drives and stimulates the nanowire growth. Thepresent study provides insight into the growth mechanism of ZnO nanowiresgrown from thermal oxidation of zinc film. Field emission measurementresults show that the prepared ZnO nanowires have excellent fieldemission properties. Uniform emission can be obtained and the turn-onfield is 7.8 V/μm. The results indicate that the method is advantageousfor large-scale synthesis of ZnO nanowires for field emission applications. [ABSTRACT FROM AUTHOR]