Photoluminescence studies in modulation doped GaInNAs/GaAs multiple quantum wells

We report for the first time the temperature dependent PL spectra from GaInNAs/GaAs triple quantum wells, modulation doped with a 2-D carrier density of ∼3×10¹¹ cm^-2 per well. The measurements were carried out at temperatures between 10 and 300K. The results are analyzed using a Gaussian fitting technique which indicates variable nitrogen composition and/or well-width fluctuations in the wells. One of the most striking features of the results is the lack of the S-Shape temperature dependence of the PL peak energy that is commonly observed in undoped dilute nitride quantum wells and is attributed to exciton de-trapping, which screens the true temperature dependence of the energy gap. Our results compare well with the predictions of the Varshni equation. The temperature dependence of the PL intensity is used to obtain the thermally activated behaviour of the non-radiative recombination processes that appear to dominate at higher temperatures.