Transmission electron microscopy and scanning electron cathodoluminescence microscopy were used to determine the effect of edge and screw dislocations on the light-emitting properties of InGaN quantum wells. Transmission electron microscopy was used to locate and identify dislocations, and cathodoluminescence studies of the same samples were used to determine the spatial variation of the luminescence. A direct correlation, between cathodoluminescence maps and transmission electron micrographs, was established which showed that threading edge dislocations acted as non-radiative recombination centres; with an associated minority carrier diffusion length of 200nm. Threading dislocations of screw and mixed type were found to be associated with surface pits which were also non-radiative in the quantum well emission. The contributions of edge and screw/mixed dislocations to reductions in quantum well emission were quantified.

Edge and Screw Dislocations as Non-Radiative Centres in InGaN/GaN Quantum Well Luminescence. D.Cherns, S.J.Henley, F.A.Ponce: Applied Physics Letters, 2001, 78[18], 2691-3