First-principles study of (Ga, Al)-codoped ZnO for optoelectronic device application

The relative stability, electronic structure, and optical properties of (Ga–Al)-codoped ZnO were investigated by first-principles calculations based on density functional theory (DFT). To study the doping effects, ZnO supercells with 32 atoms were built. The results were obtained by using Material Studios 8.0 provided by Accelrys. Ab initio spin-polarized all-electron DFT computations have been performed for substitution. The results indicate that the energy band shifts towards the higher-energy region for Al- and/or Ga-doped ZnO, which endorsed the doping of Al and/or Ga. It has been observed that the preparation of (Ga–Al)-codoped ZnO is difficult compared to Al/Ga-doped ZnO due to the considerably larger formation energy required. The imaginary part of the dielectric function e 2(ω), reflectivity R(ω), absorption coefficient α(ω), and refractive index n(ω) were calculated. The contribution of different density of states in the formation of the conduction and valence band has been analyzed for different configurations of ZnO.