Controllable preparation of 1-D and dendritic ZnO nanowires and their large area field-emission properties

• Controllable preparation of 1-D and dendritic ZnO nanowires was achieved.
• A unified growth mechanism was proposed for the different ZnO nanostructures.
• Enhanced and stable field emission was achieved from dendritic ZnO nanowires.

Large-scale one-dimensional (1-D) and dendritic ZnO nanowires were synthesized on Si substrates using a catalyst-free thermal oxidation technique. By adjusting the stress of the starting Zn thin film for the growth using an Ar ion bombardment process, controllable syntheses of samples composed of only one or a mixture of these two morphologies were achieved. Different nucleation mechanisms were proposed by detailed observations of nucleation and growth process of 1-D and dendritic ZnO nanowires. The strain-induced mass diffusion model and self-catalytic gas-liquid-solid model were used to explain the growth of 1-D and dendritic ZnO nanowires, respectively. In addition, the field-emission characteristics of ZnO nanowires were measured, which showed that dendritic ZnO nanowires have stable emission current.

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