The optical properties of non-polar InGaN/GaN multiple quantum wells grown on r-plane sapphire substrates were investigated as a function of threading dislocation density. The 6K emission spectrum consisted of a peak at 3.25eV and a broad band centred around 2.64eV. From microscopy and cathodoluminescence studies, the higher energy peak was assigned to recombination within quantum wells lying on the (1120) plane which were intersected by basal-plane stacking faults. The lower energy band was attributed to emission from sidewall quantum wells of varying width and composition which form on the various semi-polar facets of structural defects that developed during the quantum well growth.

The Effect of Dislocation Density and Surface Morphology on the Optical Properties of InGaN/GaN Quantum Wells Grown on r-Plane Sapphire Substrates. T.J.Badcock, R.Hao, M.A.Moram, M.J.Kappers, P.Dawson, C.J.Humphreys: Japanese Journal of Applied Physics, 2011, 50[8], 080201