Kinetics of free and bound excitons in GaAs/AlGaAs double heterostructures

Interplay of exciton and electron-hole plasma recombination on the photoluminescence dynamics in bulk GaAs

“…This fact suggests that the transition is ruled by exciton-phonon interaction rather than by exciton-exciton scattering. Similarly, an excitation density of 120-180x10 15 cm -3 sets a transition in the rise-time dependence on lattice temperature, which is about five times greater than the theoretical Mott transition density.…”

“…9,24 The long t r reflects the slow phonon-assisted exciton relaxation from states of large momentum k, where electron and holes were bound to form excitons, to the radiatively active states at k = 0. 14 The fast component, already seen at 13 K, has been previously observed in GaAs and tentatively attributed either to the emission of free electron-hole pairs 15 or to a rapid exciton formation mediated by LO-phonon interactions. 40 Our results discard the latter mechanism since the fast component is absent at the lowest temperature and LO-phonon emission is temperature independent.…”

“…These two facts are qualitatively identical to what is found in resistivity studies around the metal-to-insulator transition in two dimensional high mobility semiconductors. 31,32 Figure 7, shows again two groups of curves, separated by an excitation density of ~150x10 15 .…”

“…9 Thus, the literature provides a wide spectrum of experimental data with rise times increasing 10 or decreasing 7,8,[11][12][13] when raising the excitation density. On the other hand, in bulk III-V samples, these time-resolved studies are scarce [14][15][16][17] and ascertain that the free-exciton PL rise time is strongly influenced by trapping in localization centers.…”

Influence of trapping on the exciton dynamics of AlxGa1−xAs films

“…However, little attention has been paid to the luminescence dynamics of bulk GaAs, and even less to that of AlGaAs. Only recently some works, [2][3][4] which complement but not complete older scattered studies, [5][6][7][8] have investigated the emission dynamics just in GaAs, since good alloy samples have not been available. Yet, important issues in III-V alloys, such as the influence of defects or Aluminium content on the exciton dynamics, have not been addressed.…”