Cathodoluminescence study of oval defects in MBE grown InGaAs/GaAs

Semiconductor InGaAs/GaAs heterostructures grown by molecular beam epitaxy have been studied using low temperature (5K) cathodoluminescence as part of a project to determine the mechanisms of misfit dislocation nucleation. The samples studied contain oval defects which give rise to a large number of misfit dislocations. Also associated with the oval defects is a highly luminescent halo which gives rise to a peak on the low energy side of the InGaAs peak in the CL spectrum. The dislocation density is shown to oscillate along the sample and this oscillation can be partly explained by the presence of the oval defects.