Experimental evidence on low-energy electron beam-induced point defect activation in GaN grown by metal-organic vapour phase epitaxy (MOVPE) was presented. The GaN samples were irradiated with a 5 to 20keV electron beam of a scanning electron microscope and investigated by photoluminescence and positron annihilation spectroscopy measurements. The degradation of the band-to-band luminescence of the irradiated GaN films was associated with the activation of point defects. The activated defects were identified as in-grown Ga-vacancies. It was proposed that MOVPE-GaN contained a significant concentration of passive VGa-Hn complexes that could be activated by H removal during low-energy electron irradiation.

Low Energy Electron Beam Induced Vacancy Activation in GaN. H.Nykänen, S.Suihkonen, L.Kilanski, M.Sopanen, F.Tuomisto: Applied Physics Letters, 2012, 100[12], 122105