PNNL

Abstract

Transmission electron microcopy (TEM) is used to study microstructures formed in GaN irradiated with 600 keV O? ions at room temperature. Three types of defect clusters are identified in the irradiated GaN: (1) basal-plane stacking faults with dimensions ranging from 5 to 30 nm, (2) Pyramidal dislocation loops, and (3) local regions of highly-disordered material. High resolution TEM imaging clearly reveals that one type of the basal-plane stacking faults corresponds to insertion of one extra Ga-N basal-plane in the otherwise perfect GaN lattice. The interpretation of these results indicates that interstitials of both Ga and N preferentially condense on the basal plane 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 contribute to a dramatic increase in the dynamic recovery of point defects in GaN at room temperature.