Defect formation and annealing behaviours of fluorine-implanted, unintentionally doped GaN layers were studied by positron annihilation spectroscopy. Single Ga vacancies (VGa) were identified as the main vacancy-type defects detected by positron annihilation spectroscopy after fluorine implantation at 180keV with a dose of 1015/cm2. Implantation-induced VGa tended to aggregate and form vacancy clusters after post-implantation annealing in N2 ambient at 600C. Fluorine ions tended to form F-vacancy complexes quickly after thermal annealing, which was consistent with the proposed diffusion model that predicted the behaviours of fluorine in GaN.

Defect Formation and Annealing Behaviors of Fluorine-Implanted GaN Layers Revealed by Positron Annihilation Spectroscopy. M.J.Wang, L.Yuan, C.C.Cheng, C.D.Beling, K.J.Chen: Applied Physics Letters, 2009, 94[6], 061910