Microstructural and photoluminescent characterization of one-dimensional ZnO nanostructures prepared by catalyst-assisted vapour-liquid-solid technique

ZnO one-dimensional nanostructures were synthesized in thin-film form on Si substrates by the vapour-liquid-solid technique using Au as catalyst. The morphology of the ZnO nanostructures (from wire/ribbon to rod) was controlled by varying the thicknesses of the Au layers on the Si substrates. The X-ray diffraction studies of the ZnO nanostructures indicated high crystallinity and preferred orientation along the (002) plane of the wurtzite phase. The compositional analysis of ZnO nanostructures by energy-dispersive X-ray analysis revealed their chemical purity. High-resolution transmission electron microscopy indicated dislocation-free structure. The single crystallinity of the ZnO nanostructures was examined by selected-area electron diffraction. The room-temperature photoluminescence spectra of the ZnO nanostructures indicated high intensity of the ultraviolet excitonic emission. Two very week defect-related visible emissions were also observed which revealed almost a defect-free structure and good optical quality of the synthesized material.