Recombination kinetics in polar InGaN/GaN structures with wide quantum wells

We have investigated the kinetics of photoluminescence (PL) of so-called "wide" 25-nm In0.17Ga0.83N quantum wells (QW), where the studied 450 nm emission comes from excited states of the QW. These states are very closely separated and are therefore considered as a quasi-continuum of "bulklike" states. The recombination kinetics shows clear exponential behavior with time constants of 1...2 and 7...9 ns at 5 and 300 K, respectively, a behavior which indicates the dominance of radiative recombination. However, if the decay curves are resolved spectrally, a variety of kinetics is revealed, the appearance of which is likely determined by a slower energy relaxation of the photoexcited carriers in the "wide" QW. The results point to a route to improved polar optoelectronic device architectures based on "wide" QWs.