Annealing Behavior of Vacancy‐Type Defects in Mg‐ and H‐Implanted GaN Studied Using Monoenergetic Positron Beams

Vacancy-type defects in Mg-implanted GaN with and without hydrogen (H) implantation are probed by using monoenergetic positron beams. Mg+ and H+ ions are implanted into GaN(000 (1) over bar) to obtain 0.1 and 0.7-mu m-deep box profiles with Mg and H concentrations of 1x10(19) and 2x10(20)cm(-3), respectively. For the as-implanted samples, the major defect species is determined to be Ga-vacancy (V-Ga) related defects such as V-Ga, divacancy (VGaVN), and their complexes with impurities. For Mg-implanted samples, an agglomeration of vacancies starts at 800 degrees C annealing, leading to the formation of vacancy clusters such as (VGaVN)(3). For the samples annealed above 1000 degrees C, the trapping rate of positrons by vacancies is increased by illumination of a He-Cd laser. This is attributed to the capture of photon-excited electrons by the defects and their charge transition. For Mg- and H-implanted samples, the hydrogenation of vacancy-type defects starts after 800 degrees C annealing. Comparing with the annealing behavior of defects for the samples without H-implantation, the clustering of vacancy-type defects is suppressed, which can be attributed to the interaction between Mg, H, and vacancies.