Controlled Growth of Zinc Oxide Nanorod Array in Aqueous Solution by Zinc Oxide Sol-Gel Thin Film in Relation to Growth Rate and Optical Property

Our work provides a systematic study of controllable morphology, crystallinity and photoluminescence (PL) of ZnO nanorod array. Our investigation demonstrates that the pre-treatment conditions of the ZnO sol-gel thin-film have strong influences on the morphology, crystalline and PL of the ZnO nanorod arrays grown thereon. The annealing temperature of the sol-gel thin film plays an important role on the microstructure of the ZnO grains and then the growth of the ZnO nanorod arrays. As the annealing temperature increases from 130 to 900degC, the grain size of the thin films increases, and the diameter of thereon ZnO nanorod arrays increases from 60 to 250 nm. The scanning electron microscopy image show that the growth rate of ZnO nanorod along c-axis direction is very sensitive to the size of ZnO grains, and then influences the PL peak at 380 nm. The thin film annealed at the low temperature of 130degC is amorphous, but the thereon nanorod arrays are high-quality single crystals growing along the c-axis direction with a high consistent orientation perpendicular to the substrates. The as-synthesized ZnO nanorod arrays via all solution-based processing enable the fabrication of next-generation nano-devices at low temperature.