Effect of Co-doping on the structure and optical properties of ZnO nanostructure prepared by RF-magnetron sputtering

Cobalt-doped ZnO nanorods were successfully synthesized on SiO2/Si substrate using RF-magnetron sputtering at room temperature. The undoped and Co-doped ZnO nanostructures were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM). The results showed that Co2+ replaced Zn2+ in the ZnO lattice without changing the wurtzite structure. The ZnO structure became high crystallite and was gradually converted into nanorods without extra phases as increased cobalt doping levels to 3 at.% and 4 at.%. The as-synthesized nanorod arrays were dense and vertically grew on the substrate with lengths of approximately 341 and 382.3 nm for 3 at.% and 4 at.% CO, respectively. The energy bandgap values increased as the Co concentration increased to 4 at.% to reach 3.3 eV compared with undoped ZnO (3.26 eV). (C) 2013 Elsevier Ltd. All rights reserved.