Formation of zinc oxide micro-disks via layer-by-layer growth and growth mechanism of ZnO nanostructures

Zinc oxide micro-disks were fabricated by a simple vapor phase transport technique using a mixture of zinc oxide and graphite powders. The crystal structure of the synthesized samples was examined by X-ray diffraction and Raman spectroscopy. The morphology of the samples was observed using field emission scanning electron microscopy. The observed formation of disks suggests that preferential growth along the [0 0 0 1] direction is suppressed and the growth takes place mainly along the six directions of the 〈1010¯〉 plane. Based on our experimental results, we propose a layer-by-layer growth mechanism and qualitatively explain the suppressed growth along the [0 0 0 1] direction. Our results provide useful information on the growth mechanism of ZnO nanostructures.