Optical properties of well-aligned ZnO nanostructure arrays synthesized by an electric field-assisted aqueous solution method

A simple electric field-assisted aqueous solution (EFAS) technique was successfully developed to prepare 1D ZnO nanostructures with different morphologies. Changing the current density between the substrate and the Pt wire as the anode can efficiently control the morphologies of the nanostructures. The structural and optical properties of the ZnO nanostructures including nanorods and nanocones were investigated by photoluminescence and Raman spectroscopy. Raman spectrum measurements confirmed that the ZnO nanorod arrays were vertically aligned and highly c-axis oriented, with the sample treated at 0.05 mA demonstrating the best crystallization among all samples. The optical quality of the as-grown ZnO nanocones improved after thermal annealing at 500 °C because of the released functional group elements and decreased deep-level defects. These findings indicate the potential of the EFAS method to grow high-quality ZnO nanostructures for field-emission and optical applications.