Randomly oriented ZnO nanowires grown on amorphous SiO 2 by metal-catalyzed vapour deposition

Abstract

Randomly oriented ZnO nanowire (NW) networks have been grown on thermal SiO 2 substrates by the simple carbothermal reaction-assisted thermal evaporation of ZnO. One-dimensional growth was achieved with the aid of Au nanocluster catalysts dispersed on the substrates. The structures were studied by scanning electron microscopy, energy dispersive X-ray analysis, and X-ray absorption spectroscopy. The NW diameters and lengths were found to strongly depend on the substrate temperature ( T S) and to be in the 5–10 nm and 40–110 nm ranges for T S = 520 °C, and in the 50–80 nm and 1–3 μm ranges for T S = 700 °C, respectively. The growth regime was characterized by comparing the NW structures obtained on SiO 2 with those grown in the same deposition run on (1 0 0) Si substrates also covered with the Au catalyst. The NW structure prepared at 700 °C behaves as a dense NW network with net electrical conductance and persistent photoconductance. These results suggest a method to deposit size-controlled ZnO NW networks on insulating cost-effective substrates with important potential applications as in chemical sensors and solar cells.