The effect of dislocation density and surface morphology on the optical properties of InGaN/GaN quantum wells grown on r-plane sapphire substrates

The optical properties of non-polar InGaN/GaN multiple quantum wells grown on r-plane sapphire substrates are investigated as a function of threading dislocation density. The 6 K emission spectrum consists of a peak at 3.25 eV and a broad band centred around 2.64eV. From microscopy and cathodoluminescence studies, the higher energy peak is assigned to recombination within quantum wells lying on the (1120) plane which are intersected by basal-plane stacking faults. The lower energy band is attributed to emission from sidewallquantum wells of varying width and composition which form on the various semi-polar facets of structural defects that develop during the quantum well growth. © 2011 The Japan Society of Applied Physics.