Damage evaluation processes in patterned GaN implanted by 3 MeV Au2+ ions were investigated as a function of ion fluences and annealing temperatures. Surface swelling was observed by using atomic force microscopy and the results showed that the swelling height depends on ion fluence and annealing temperature. The authors observed four-stage implantation-induced damage evolution including point-defect formation, defect clustering, amorphization/bubble formation, and eventually, decomposition. This evolution is contributed to irradiation-induced defect production and defect migration/accumulation occurred at different levels of displacement per atom. Craterlike holes were observed on the surface of GaN implanted at the ion fluence of 2x10(16) cm(-2), which is evidence of N loss, and broken bubbles formed during implantation.