The enhancement of near-band-edge emission by hydrogen plasma treatment for Ga-doped ZnO, ZnO and ZnMgO films

Abstract Hydrogen (H) plasma treatment has been used to improve the optical properties of ZnO-based materials. Giant 83-fold and 105-fold enhancement ratios of near-band-edge (NBE) emission are obtained in H-plasma treated ZnO and ZnMgO films, respectively, while a relatively small 8.6-fold enhancement ratio occurs to Ga-doped ZnO film. The NBE enhancement is partly attributed to the introduction of additional radiative recombination centers through H-plasma treatment. In addition, the passivation of nonradiative recombination centers by H accounts for partial NBE enhancement. The pronounced NBE enhancement differences among ZnO, ZnMgO and Ga-doped ZnO films can be illustrated as follows: on one hand, Ga ion with positive trivalence is more repulsive to H ion with positive univalency compared with Zn and Mg ions, resulting in the decrease of the concentration of H in Ga-doped ZnO film; on the other hand, the passivation of nonradiative recombination centers by H is more prominent in ZnMgO due to the poorer quality of ZnMgO.