Density functional theory study for polycrystalline ZnO doped with Si or Nb

We present a density functional theory analysis for polycrystalline ZnO doped with the potential multiple donors silicon and niobium. A self-interaction correction allows a more accurate description of the defect formation energies as well as the additional electronic doping levels, which enable us to evaluate the influence of Si and Nb doping on the optical transparency and electrical conductivity of ZnO. According to our study, Si and Nb point defects in the bulk crystal or at grain boundaries lead to electronic dopant levels that may explain the high electrical n-type conductivity combined with the high transparency achieved by several experimental groups.