Effects of annealing on the luminescent properties from defects formed in electron-irradiated GaN

The effects of annealing on the luminescence properties of electron-irradiated GaN were investigated by photoluminescence (PL), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Our results indicate that the yellow luminescence (YL) remains disappear after all annealing treatments and shows a non-linear dependence on the annealing temperature up to 800 °C. The annealing process can be divided into two main stages associated with irradiation defects. At annealing temperatures up to 600 °C, the behavior of YL can be attributed to the net effects of VGaON complex formation caused by the migration of gallium vacancies (VGa) and VGaON complex dissociation due to the disappearance of gallium vacancies. At annealing temperatures approaching 800 °C, the incorporation of carbon into the group-V sublattice becomes the dominant factor in the appearance of YL. In addition, experimental results of PL and SEM show that a small proportion of irradiation damage still exists in GaN after annealing at 800 °C. ► Electron-irradiated GaN exhibits a non-linear dependence on the annealing temperature up to 800 °C. ► The origin of YL in the whole annealing process is relative with two defect complexes. ► The behavior of YL below 600 °C annealing is attributed to the VGaON complexes. ► The incorporation of carbon into the group-V sublattice should be responsible for the increase of YL at 800 °C.