Strain-related recombination mechanisms in polar InGaN/GaN MQWs on amorphous SixC1-x buffers

PL dynamics of InGaN/GaN multiple quantum well (MQW) LEDs grown on SixC1-x/SiO2/Si substrates were measured in order to explore the real carrier recombination mechanism related to existing strain in polar MQWs, which took advantage of well strain control on GaN/ SixC1-x interfaces by varying x value. Contrary to earlier reports, the exciton localization model was found to be better at describing the non-exponential decay of PL than the bi-molecular recombination model, which indicated that the correlation between the electron and the hole could not be ignored in polar MQWs. Progressive strain surprisingly accelerated the radiative recombination in MQWs accompanied by accelerating nonradiative recombination. This was attributed to the enhanced formations of fast localized recombination centers associated with well thickness variations.