Transmission electron microscopy was used to study the microstructures formed in GaN irradiated with 600keV O+ ions at room temperature. Three types of defect cluster were identified in the irradiated GaN. These were: basal-plane stacking faults with dimensions ranging from 5 to 30nm, pyramidal dislocation loops and local regions of highly disordered material. High-resolution transmission electron microscopic imaging clearly revealed that one type of basal-plane stacking fault corresponded to the insertion of an extra Ga-N basal plane into the otherwise perfect GaN lattice. The interpretation of these results indicated that interstitials of both Ga and N condensed preferentially onto the basal plane so as to form a new layer of Ga-N under these irradiation conditions. The formation of these extended defects, and their interactions with the point defects produced during irradiation, contributed to a marked increase in the dynamic recovery of point defects at room temperature.

Defect Clustering in GaN Irradiated with O+ Ions. C.M.Wang, W.Jiang, W.J.Weber, L.E.Thomas: Journal of Materials Research, 2002, 17[11], 2945-52