Transmission electron microscopy was used to examine the core structure of threading dislocations in heavily Mg-doped Al0.03Ga0.97N thin films. It was shown that edge and mixed, but not screw, dislocations had hollow cores with typical diameters of 1 to 5nm. A model was presented in which hollow core formation was initiated by the segregation and subsequent precipitation of Mg at these dislocation cores.

Observation of Coreless Edge and Mixed Dislocations in Mg-Doped Al0.03Ga0.97N. D.Cherns, Y.Q.Wang, R.Liu, F.A.Ponce: Applied Physics Letters, 2002, 81[24], 4541-3