Morphology and optical properties of ZnO microrods grown by high-temperature hydrothermal method

Abstract

The ZnO microrods were fabricated on a fluorine-doped tin oxide (FTO) glass by using a high-temperature hydrothermal method. The main goal is to investigate the correlation between synthesis temperature and characteristics of ZnO microrods. The morphology of ZnO microrods was investigated by field-emission scanning electron microscope (FESEM), the optical properties were measured by photoluminescence (PL), and the crystallinity was characterized by X-ray diffraction (XRD). SEM images show that morphology of ZnO is rod-like. The growth mechanism is explained by Oswald ripening process. The outer surface, length, top-end, and bottom diameter of ZnO microrods, however, vary with the synthesis temperatures. The synthesis temperatures are associated with pH values and the pH value is related to cation concentration in the solution. Thus Zn ion concentration plays an important role in controlling the morphology of microrods. In this study it is found that ZnO microrods grown at 90°C have the best crystallinity and fewer defects with preferred optical properties than other samples.