Growth Behavior, Microstructure Characterization, and Field-Emission Property of 6-Fold Hierarchical Zn/ZnO Structures Prepared by Direct Annealing

Abstract

Six-fold core-shelled three-dimensional hierarchical structures were prepared by a direct annealing process. The effect of experimental parameters on density and length of branches of hierarchical Zn/ZnO structure is discussed. The influence of oxide layer formation and the shape of Zn polyhedron on the relaxation of stress for nanostructure growth also is reported. At the annealing temperature of 375 °C, the largest aspect ratio (∼71) of branched nanostructures and the smallest density (0.05 tips/μm2) of hierarchical arrays can be obtained. Transmission electon microscopy analysis shows that the oxide layer grows epitaxially from the Zn microtips and then the branches grow epitaxially from the oxide layer. For field emission applications, a better turn-on electric field (8.5 V/μm) and a larger enhancement factor 3490 are obtained for branched nanostructures with the high aspect ratio.