Influence of Co Doping on the Structural and Optical Properties of ZnO Nanostructures

Undoped and 2.5 % Co doped ZnO nanostructures have been synthesized by simple chemical method at the temperature of 65 degrees C. The prepared samples are characterized by X-ray diffraction (XRD) analysis, UV-visible absorption (UV-Vis) and photoluminescence (PL) emission spectroscopy. The XRD results indicate that the synthesized ZnO powders are a pure single phase wurtzite structure and also it is found that the lattice parameter of the synthesized ZnO nanostructure varies due to Co doping. It is also found that PL emission and UV-Vis absorption peaks are red shifted due to Co incorporation in ZnO. The results confirmed that Co is incorporated as Co2+ in the core of these nanocrystals, occupying the Zn2+ sites in the wurtzite structure of ZnO. Localized selected area electron diffraction (SAED) patterns shows that the nanorods are single crystals. The UV PL emission band of doped ZnO nanorods exhibits a red shift from 382 to 386 nm, indicating a band-edge bending due to the presence of doping material in ZnO nanostructure. The defect-related PL emission band centered at 600 nm observed in undoped ZnO sample is suppressed considerably in doped nanorods, revealing the quenching of surface defects present in the synthesized materials.