Rational doping for zinc oxide and its influences on morphology and optical properties

Zinc oxide (ZnO) nanopowders doped with different metal ions (Me, Me = Sn4+, In3+, Mn2+, and Co2+) are prepared by a simple sol-gel method. Influences of the ion doping on morphology and optical properties of the resulting ZnxMeyO are investigated by scanning electron microscopy, X-ray diffraction, UV-vis absorption spectrum, and photoluminescence. The morphology of ZnO can be tailored by ion doping, which is closely related not only to the ionic radii and electronegativities of the doped ions, but also to their oxidation states and electron configurations. The optical band gap and photoluminescence of ZnO can also be modulated by ion doping, which results from a combination of different effects, Burstein-Moss, band tail, charge compensation, sp-d exchange, non-radiative recombination, and blocking barrier. This may offer us a viable approach to tuning the (optical) properties of ZnO-based materials via rational ion doping.