Luminescence of InGaN MQWs grown on misorientated GaN substrates

Optoelectronic devices based on InGaN have already been commercialised, however, the Indium content is limited to around 5%. With higher Indium concentration the quantum efficiency decreases, which is thought to be due to increasing inhomogeneity. In this work it is shown that the growth of InGaN on misorientated GaN substrates forces these Indium fluctuations on a nanometre scale. Temperature dependent luminescence measurements provide information about the homogeneity of the band structure. Energy selective excitation confirms the existence of localisation centres and indicates their energetic depth. Time-resolved measurements define the lifetime of localized excitons, which provides information about radiative and nonradiative processes as well as tunnelling mechanisms between the localization centres. Indium fluctuations at the nm and μm scale are measured using cathodoluminescence (CL) and Micro Photoluminescence (μPL) respectively.