Two types of threading dislocation with edge components were investigated by means of the high-resolution transmission electron microscopy of undoped GaN epilayers which were grown onto Al2O3 substrates. One type had a fully-filled core, with a regular contraction and stretching of bright dots. The other was incompletely filled, with one bright dot less and an irregular contraction and stretching of bright dots. The latter were distorted, and degenerated into bright line segments at cores in areas with smaller local dislocation intervals. The results suggested that the distorted bright regions were due to glide and/or climb which was caused by nearby dislocation interactions.

Threading Dislocations with Edge Components in GaN Epilayers Grown on Al2O3 Substrates. J.Kang, T.Ogawa: Journal of Materials Research, 2001, 16[9], 2550-5