It was demonstrated that, when vertical threading dislocations in (00▪1) GaN were imaged in plan-view by transmission electron microscopy, a surface-relaxation contrast operated in addition to that due to the strain fields of dislocations passing through the specimen. It was shown that all three dislocation types (edge, screw, and mixed) could be detected in the same image using g=(11▪0) and 18° specimen tilt from [00▪1], allowing total densities to be assessed properly. The type of an individual dislocation could also be readily identified.

Plan-View Image Contrast of Dislocations in GaN. D.M.Follstaedt, N.A.Missert, D.D.Koleske, C.C.Mitchell, K.C.Cross: Applied Physics Letters, 2003, 83[23], 4797-9