Defect-curing effects of fast neutrons on n-type GaN

The defect-curing effects of fast neutrons have been studied using single-crystalline GaN samples irradiated under four different neutron fluences. The conditions of each neutron irradiation were quantified by gamma-ray spectroscopy. We found that some defects generated during GaN crystal growth were cured at a low neutron fluence, and at a certain irradiation condition, the number of cured defects were larger than that of newly produced defects. Electrical parameters of Schottky barrier diodes fabricated by using samples from every batch demonstrated different levels of defect-curing effects. In terms of optical characteristics, the defect-curing effects were checked by photoluminescence spectroscopy measurements. Through synchrotron X-ray topography characterization, the number of cured, newly generated, and altered defects were quantified and directly confirmed the curing effects of fast neutrons.