Behavior of excess donor-like defects induced by implantation of various ion species and subsequent annealing in n-type GaN layers

Abstract Donor-like defects induced by Si-ion implantation and subsequent annealing cause an excess net donor concentration ( N D ) in GaN, which makes precisely controlling N D in devices difficult. To clarify the origin of the donor-like defects, this study investigates N D distributions in GaN layers implanted with various neutral or donor elemental ions before the samples are annealed. The implantation of Al ions as neutral species in GaN resulted in an increase in N D along the implantation profile after annealing at 1100 °C, similar to the effect of Si-ion implantation. This suggests that donor-like defects originate from intrinsic defects rather than from impurities. By contrast, excess N D was suppressed near the concentration peaks for N and O ions that mostly substitute at N sites in GaN. These results suggest that N vacancies are presumably responsible for the excess N D and that their formation is suppressed by implantation of ions substituting at N sites.