Cathodoluminescence studies were carried out on a 30nm GaN/1.5nmIn0.28Ga0.72N/(00•1) GaN single quantum well structure in a field emission scanning electron microscope at voltages below 5kV and temperatures down to 8K. A direct comparison of cathodoluminescence maps with transmission electron microscope studies carried out on back-thinned samples showed that the quantum-well emission was reduced close to defects identified as V-shaped pits and around threading edge-type dislocations. Extended area cathodoluminescence spectra showed progressive blue-shifting in the quantum-well emission from around 460 to about 445nm as the electron dose increased. This blue-shift, which could be reversed by exposure to ultra-violet light, was accompanied by degradation in the spatial resolution of quantum-well cathodoluminescence maps consistent with an increase in the carrier diffusion length from 200 to 330nm. It was proposed that these effects could be explained by filling of the trap states in the vicinity of the quantum well by free carriers generated during irradiation.

Cathodoluminescence Studies of Threading Dislocations in InGaN/GaN as a Function of Electron Irradiation Dose. S.J.Henley, D.Cherns: Journal of Applied Physics, 2003, 93[7], 3934-9