Room temperature excitonic recombination in GaInN/GaN quantum wells

Abstract

The dependence of radiative and nonradiative lifetimes on the excess carrier density in GaInN/GaN quantum wells is studied via time-resolved photoluminescence spectroscopy over a wide range of excitation densities. Our results differ from the predictions of simple free-carrier models: density independent radiative lifetimes clearly evidence the excitonic nature even at room temperature. At high densities, nonradiative lifetimes are weakly temperature dependent and proportional to the inverse of the density, implying an excitonic, threshold-less Auger process. Furthermore, in the intermediate density regime between low and high injection, an increase of the nonradiative lifetimes is observed, which is typical for Shockley-Read-Hall-type recombination.