Structural and photoluminescence properties of Co-doped ZnO nanorods prepared by RF-magnetron sputtering

Cobalt-doped ZnO nanorods were successfully synthesized on SiO2/Si substrate using RF-magnetron sputtering at room temperature. The structural, morphological, and photoluminescence (PL) properties of undoped and Co-doped ZnO nanostructure were characterized using X-ray diffraction, field emission-scanning electron microscopy, and PL analyses. The results showed that Co2+ replaces Zn2+ in the ZnO lattice without changing the wurtzite structure. As the Co concentration increases, the structure becomes highly crystalline and is gradually converted into nanorods with no extra phases. The as-synthesized nanorod arrays are dense and vertically grow on the SiO2 substrate. The arrays exhibit diameters of approximately 56.89 nm as well as lengths that range from 247.9 nm to 527.5 nm. PL analysis reveals that the ultraviolet (UV) emission intensity decreases and exhibits a blue shift as the Co doping level is increase.