Growth of spatially ordered ZnO nanowire arrays for field emission applications
Garry, Seamus (2013) Growth of spatially ordered ZnO nanowire arrays for field emission applications. PhD thesis, Dublin City University.
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In this work the growth of spatially ordered and vertically aligned ZnO nanowires is examined. Nanowire arrays are grown using chemical bath deposition (CBD) and carbothermal reduction vapour phase transport (CTR-VPT) techniques. Nanosphere lithography (NSL) was used to achieve spatial ordering of these arrays; arrays with inter-wire distances of 500 nm, 1.0 μm, and 1.5 μm were grown using both CBD and CTR-VPT techniques. Two distinct implementations of the NSL technique are investigated, one which relied on the deposition of a catalyst material and one which involved the deposition of a secondary mask which prevents ZnO deposition from occurring in undesired areas. The field emission (FE) characteristics of these arrays were examined, revealing a significant dependence of the FE properties on both nanowire morphology and array density. A geometric factor is calculated which is dependent on both nanowire aspect ratio and the density of nanowires in an array and this factor has been found to correlate with other indicators of FE properties. The results presented in this work may be useful in informing the design of ZnO nanowire arrays in order to maximise their FE efficiency and uniformity.
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