Preparation and optical properties of Co doped nano-ZnO arrays

Firstly, ZnO seed layer thin films were successfully prepared on silicon substrates by radio frequency magnetron sputtering method. The seed layer substrate was treated at high temperature of 400 degrees C and placed vertically on the substrate in a high-pressure reactor. Co/ZnO nanorod arrays with good dispersibility were synthesized by hydrothermal synthesis at 100 degrees C on the ZnO seed layer using Zn(CH3COO)2<middle dot>2H2O as the zinc source, NaOH as the analytical reagent, and C4H6CoO4<middle dot>4H2O as the cobalt source. The structure, morphology, and optical properties of the samples were characterized and analyzed in sequence. The results indicate that the sample exhibits strong diffraction peaks on the crystal plane (002, 101, 102) and the growth of the (002) crystal surface is preferred. The prepared samples are hexagonal wurtzite structure. With the increase of Co doping molar ratio, the uniformity of the samples gradually becomes worse, while the average diameter of ZnO nanorods becomes larger. The PL spectrum shows that the sample has a strong ultraviolet emission peak at around 372 nm, and a significant red shift has occurred. Besides, there is a relatively weak visible light emission peak appeared near 565 nm. Finally, the growth mechanism and luminescence mechanism of nano-Co/ZnO arrays are explained.