Recombination processes and photoluminescence intensity in quantum wells under steady-state and transient conditions

We present a theoretical and experimental study of recombination processes in quantum wells. Our model calculations, which include free-excitonic, free-carrier, and defect-mediated nonradiative recombination, describe the dependence of the photoluminescence intensity on excitation density under steady-state conditions and on time under transient conditions. For the former conditions, it is not, in principle, possible to distinguish between excitonic and free-carrier contributions to the photoluminescence intensity. However, an accurate determination of the relative weight of nonradiative and radiative contributions can be made. For transient conditions, on the other hand, excitonic contributions may be identified, while the discrimination between radiative and nonradiative contributions is—though possible—possessed with ambiguities. We finally apply our model to a set of experimental data, taken at 300 K from a single ${\mathrm{In}}_{0.1}$ ${\mathrm{Ga}}_{0.9}$As/${\mathrm{Al}}_{0.33}$ ${\mathrm{Ga}}_{0.67}$As quantum well under both steady-state and transient conditions. The results of this analysis demonstrate the consistency of our model and its potential for the quantitative understanding of the recombination dynamics in quantum wells.