Growth of highly uniform size-distribution ZnO NR arrays on sputtered ZnO thin film via hydrothermal with PMMA template assisted

This paper demonstrates a fabrication approach to control size distribution of zinc oxide nanorod arrays (ZnO NRAs) when using a polycrystalline seed layer. Through perfect matching between a physical confinement using a periodic PMMA template and a chemical confinement via hydrothermal method, highly ordered ZnO NRAs are accomplished. This matching relies on the restricted nucleation sites where the seed layer's grain size as well as number of grains along the template's aperture become dominant factors. In the experiment, various dimensions of periodic templates and precursor concentrations were carried on. The optimum condition shows single-ZnO NR arrays with good uniformity. Multiple rod array appears in the template with larger holes' dimension as it allows multiple nucleation sites to be formed. The effect of spacing between holes in the template is also included. The results demonstrate an effective and cost-effective way for tailoring uniformity of single ZnO NRAs on the polycrystalline seed layer.