Biexciton kinetics in GaN quantum wells: Time-resolved and time-integrated photoluminescence measurements

We report on the experimental achievement of narrow ultraviolet excitonic and biexcitonic emission from GaN/AlGaN quantum wells. The very large biexciton binding energy (up to 12 meV) inhibits thermalization between the two species allowing to study the recombination kinetics of the biexciton gas. By performing resonant and nonresonant time resolved measurements, we elucidate the interplay between biexciton formation and exciton acoustic-phonon mediated relaxation within localized states

Impact of quantum confinement and quantum confined Stark effect on biexciton binding energy in GaN/AlGaN quantum wells

We report on time-resolved photoluminescence measurements carried out along the thickness gradient of two types of GaN/AlGaN quantum wells with low Al content in the barriers (5% and 9%, respectively). A reduction of the biexciton binding energy with increasing well thickness is observed, as a result of the reduced quantum confinement and the increasing impact of the quantum confined Stark effect. In the sample with 5% Al content in the barriers, for thicknesses of the well region larger than similar to 9 monolayers, the biexciton binding energy is found to be smaller than that measured for bulk GaN. (c) 2008 American Institute of Physics

Quantum confinement dependence of the energy splitting and recombination dynamics of A and B excitons in a GaN/AlGaN quantum well

We report the observation of well-resolved A and B excitonic resonances in the reflectivity spectra of a wedged GaN/AlGaN quantum well (QW) with 5% Al content in the barriers for different well thicknesses. For the thicker well cases, the energy splitting between the A and B excitons is larger than the one found for bulk GaN. However, the A-B exciton energy splitting decreases with decreasing well thickness, accordingly to the delocalization of the electron and hole wave functions in very thin QWs, as supported by theoretical simulations. Moreover, we used time-resolved photoluminescence measurements to investigate the recombination dynamics of the two excitonic states demonstrating the existence of a thermodynamic equilibrium between the two populations at a sample temperature of 10 K

Strong Light-Matter Coupling in GaN-Based Microcavities Grown on Silicon Substrates

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