The effect of the post-growth annealing on the electroluminescence properties of n-ZnO nanorods/p-GaN light emitting diodes

In this paper we investigated the effect of post-growth annealing treatment on the electroluminescence (EL) of n-ZnO nanorods/p-GaN light emitting diodes. The ZnO nanorods were grown by the low temperature (<100 °C) aqueous chemical growth (ACG) technique. The as-grown ZnO nanorods were annealed in nitrogen, oxygen, argon, and air ambients at 600 °C for 30 min. The electroluminescence (EL) measurements showed that the deep level defects related emissions in ZnO were greatly affected by the annealing of the n-ZnO nanorods in different ambients. By comparing the EL spectra of ZnO nanorods annealed in different ambients it was found that nitrogen annealing ambient is very effective in shifting the emission peak from the green region to the red region. It was also concluded that the red emission in ZnO was attributed to oxygen vacancies (Vo). The effect of the annealing ambient and the temperature dependence electroluminescence were discussed with relation to the intrinsic and extrinsic defects.