Experimental results obtained for H-implanted GaN were presented. The ion energies ranged from 100 to 850keV, and the implantation fluence ranged from 5 x 1013 to 1018/cm2. The data obtained with a slow positron beam showed that vacancy clusters were formed in as-implanted samples with fluences above 1017/cm2. Below this value, only single vacancies were detected after implantation, but vacancy clusters could be formed and subsequently dissociated by thermal annealing.

Vacancy Profiles and Clustering in Light-Ion-Implanted GaN and ZnO. F.Tuomisto: Applied Surface Science, 2008, 255[1], 54-7