Role of hydrogen co-doping on opto-electronic behaviors of Na-H co-doped zinc oxide: a first principle study

In this work, the electronic structure and optical properties are investigated within the framework of the density functional theory (DFT) for different Na-H co-doping scenarios to find out the suitability of H co-doping technique for achieving p-type conductivity in ZnO. Very low formation energies were found for the H co-doped systems compared to others which suggests that they can suppress other n-type impurities and increase the effect of p-type Na Zn defects in the lattice. From the electronic structure calculations, we have found that Na Zn doped structures with 50% H co-doping produces the best p-type behavior indicating importance of controlling annealing time. Moreover, from the optical calculations, it has been found that Na Zn creates impurity states 174 meV above the valence band and electron concentration in these states can be controlled by H co-doping concentration. H co-doping has not produced any substantial lattice strain as compared to other dopants and structures with Na-H co-doping is transparent in the visible light range.