The origin of the green gap for GaInN/GaN quantum wells is investigated via temperature-dependent time-resolved photoluminescence spectroscopy. A strong correlation between nonradiative lifetimes and total strain energy is observed, although the wells are almost fully strained. We discuss this observation in terms of nonradiative recombination at defects which contribute to a beginning partial relaxation. The formation energy of a defect is likely reduced by the amount of its released strain energy. We therefore expect an exponential dependence of the defect density on this released strain energy. Our measured nonradiative lifetimes are consistent with a cumulative strain driven generation of defects.
Nonradiative loss processes are a major concern in nitride-based light emitting devices. Utilizing optical gain measurements on GaInN/GaN/AlGaN laser structures, we have studied the dependence of the total recombination rate on excess carrier density, up to rather high densities. From a detailed quantitative analysis, we find a room-temperature Auger recombination coefficient of 1.8 ± 0.2 × 10−31 cm6/s in the bandgap range 2.5 − 3.1 eV, considerably lower than previous experimental estimates. Thus, Auger recombination is expected to be significant for laser diodes, while it is not likely to be a major factor for the droop observed in light-emitting diodes.
We have studied the growth of GaInN/GaN quantum wells on various polar, nonpolar and semipolar planes. From a detailed x-ray diffraction analysis, we derive the strain state and the composition of the quantum wells. The optical emission energy is obtained from photoluminescence spectra and modelled taking into account the deformation potentials and the Stark shifts. Both x-ray and optical data consistently show that indium incorporation is identical on the polar, nonpolar and semipolar planes within the experimental uncertainty.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.