Vacancy-type defects and their annealing behaviors in Mg-implanted GaN studied by a monoenergetic positron beam

Vacancy-type defects in Mg-implanted GaN were probed using a monoenergetic positron beam. Mg ions of multiple energies (15-180 keV) were implanted to provide a 200-nm-deep box profile with Mg concentration of 4 x 1019 cm(-3). The major defect species of vacancies introduced by Mg-implantation was a complex between Ga-vacancy (V-Ga) and nitrogen vacancies (V-N(S)). After annealing above 1000 degrees C, these defects started to agglomerate, and the major defect species became (VGa) 2 coupled with V-N(S). The defect reaction occurred between not only the defects introduced by the implantation but also the defects introduced by an excess Mg-doping. The depth distribution of vacancy-type defects agreed well with that of implanted Mg, and no large change in the distribution was observed up to 13008 degrees C annealing. Relationships between photoluminescence bands and vacancy-type defects introduced by Mg-implantation are also discussed. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim