Abstract: Based on the primary principle of density functional theory (DFT) system, five super-cell models of the pure ZnO, Cd doped ZnO, Cu doped ZnO, Cu-Cd co-doped ZnO, and Cu-2Cd co-doped ZnO, were optimized respectively for their geometric structure. The cell structure, energy band structure, state density, and their optical properties such as the imaginary component of dielectric function, absorption rate and reflectivity of each system were calculated and analyzed. The investigation result showed that the single doping of Cu or Cd could increase the carrier concentration of the ZnO and make the conductivity of ZnO improved. Never the less, in the case of Cu-Cd co-doping, the state of ZnO system would be more stable due to lower E. In connection with optical properties, the Cd-doping would make red shift of the edge of the ultraviolet region and the absorption would be slightly enhanced. When the ZnO was doped by Cu and Cu-Cd co-doped, the absorption coefficient of the system at the visible light and ultraviolet band would increase remarkably, making the photocatalytic activity of ZnO enhanced. When the characteristics single doping of ZnO with Cu and Cd was taken into consideration, the Cu-Cd co-doping of ZnO would make the semiconductor produce different transmittance if the doping concentration of Cd was controlled. So that the transparent devices with different efficiency could be propered by managing the doping of ZnO with different ratio of Cu-Cd.

Key words: Cu-Cd co-doping, primary principle, electronic structure, optical properties