Influence of RTA treatment on the physical properties of well-aligned ZnO nanorods

Well-aligned zinc oxide (ZnO) nanorod structures were grown on ZnO-coated (seed layer) glass substrates using a simple and low-cost aqueous solution method at a growth temperature of ∼70 °C. The physical properties were examined at room temperate using appropriate techniques. After preliminary analysis, the structures were heat treated at different temperatures varying from 300 to 800 °C using the rapid thermal annealing technique under N₂ environment for 1 min and investigated the influence of annealing effect on their physical properties. The as-grown ZnO nanorods are slightly zinc-rich in nature and exhibited hexagonal wurtzite structure. These nanorods are uniformly grown along the [0 0 1] direction and their average length and diameter are found to be ∼1.0 μm and ∼85 nm, respectively. While increasing annealing temperature, the oxygen content and crystallinity of the ZnO nanorods increased up to 600 °C, and above this temperature, the oxygen content increased continuously whereas the crystallinity of the nanorods decreased. The electrical resistivity of nanostructures slightly increased with the increase of annealing temperature probably due to the damage in their columnar structure.