Cathodoluminescence technique combined with transmission electron microscopy (TEM-
CL) has been used to characterize optical properties of dislocations in GaN epilayers. The
dislocations act as nonradiative centers with different recombination rates. TEM-CL
observation showed that even for the same Burgers vector of a, the dislocations show
different electrical activity depending on the direction of dislocation line, ie, the edge-type
dislocation parallel to the c plane is very active, while the screw-type one is less active. The …