Cobalt is a typical element
in transition metals because of its abundant energy states of electron and which can be used to tune both the optical and
magnetic properties of ZnO. Therefore, the investigations on optical properties of Co 2+ doped ZnO nanomaterial s are rather important for fundamenta l research and practical applications. Semiconductor materials doped with a few percent of transition metals [dilute magnetic semiconduc tors (DMSs)] can exhibit potential applications in spintroni c devices, which take advantage of both electron charge and spin in device operation.