Carrier recombination dynamics in InxGa1-xN/GaN multiple quantum wells

We have measured the carrier recombination dynamics in InGaN/GaN multiple quantum wells over an unprecedented range in intensity and time by means of time-resolved photoluminescence spectroscopy. We find that, at times shorter than 30 ns, they follow an exponential form and a power law at times longer than 1 mu s. To explain these biphasic dynamics, we propose a simple three-level model where a charge-separated state interplays with the radiative state through charge transfer following a tunneling mechanism. We show how the distribution of distances in charge-separated states controls the dynamics at long time. Our results imply that charge recombination happens on nearly isolated clusters of localization centers.