Recombination dynamics of excitons and biexcitons in a hexagonal GaN epitaxial layer

Abstract

Time-resolved photoluminescence (PL) spectroscopy has been performed at 18 K on excitonic-related emissions in an unintentionally doped hexagonal GaN epitaxial layer grown by two-flow metalorganic chemical vapor deposition (TF-MOCVD). Under low excitation condition, radiative recombination of A free exciton (EXA: 3.4921 eV) and neutral shallow-acceptor bound exciton [(A0s,X): 3.4805 eV] dominated the spectrum. Decay time of (A0s,X) emission is relatively long (585 ps) indicating a small number of non-radiative centers in the layer. At higher excitation densities, new PL peak appeared at 3.4864 eV and grew superlinearly with excitation densities. These features, combined with their transient behavior, suggest that this new emission band is due to the biexciton recombination.

Dynamics of the Bound Excitons in GaN Epilayers Grown by Hydride Vapor Phase Epitaxy

“…The strong doublet peak in the PL at 3.4781 and 3.4792 eV corresponds to the neutral-donor-bound exciton (labeled D 0 X). The sharp peak at 3.4732 eV is the acceptor-bound-exciton transition (marked A 0 X 1 ) [12,13]. Finally, the weaker doublet peak at 3.4607 and 3.4621 eV we assign, in agreement with Refs.…”

Impact of biexcitons on the relaxation mechanisms of polaritons in III-nitride based multiple quantum well microcavities

“…27 In bulk GaN, the biexciton binding energy is of the order of 5.7 meV. 28,29 In systems of reduced dimensionality, the biexciton binding energy varies in a nontrivial way as it depends on the confinement, the disorder, and the amplitude of the quantum-confined Stark effect inherent to III-nitride based heterostructures grown along the polar c axis. 30 In any case, in high-quality nitride-based MQW MCs, where the biexciton binding energy exceeds the exciton inhomogeneous broadening, it should be possible to observe additional emission features linked to the existence of biexcitons.…”

Excitonic Thermalization and Recombination in Homoepitaxial Gallium Nitride

“…[7]) which can be due to donors with different chemical origin. The line D* at 3.476 eV is close to the position expected for emission from biexcitons [4,9], however, its lifetime, (60 AE 10) ps is as long as the excitonic one in contradiction to the biexciton hypothesis. Its dynamics suggests that it can be attributed to an excited state of the DBE as found in magnetooptic measurements [10].…”