Carrier trapping effects on photoluminescence decay time in $InGaN∕GaN$ quantum wells with nanocluster structures

Carrier dynamics in $InGaN∕GaN$ quantum wells (QWs) with compositional fluctuations is studied with time-resolved photoluminescence (PL) experiments and Monte Carlo simulations of exciton hopping and recombination. In particular, the effects of indium-rich nanoclusters in such a QW structure on the photon-energy-dependent PL decay time are investigated. In our experiments, two $InGaN∕GaN$ QW samples of different silicon doping conditions are used for demonstrating the two cases of different nanocluster densities. An increasing trend of PL decay time on the high-energy side of the PL spectrum is observed in the sample with high nanocluster density. Such a trend is not observed in another sample with few clusters. This difference is consistent with the simulation results which can help us in identifying the origin of the increasing trend as exciton trapping by the local potential minima in the spectral range of the free-carrier states.