Exciton dark states in the recombination kinetics of InAs quantum dots

Abstract

Time‐resolved photoluminescence experiments in high quality InAs/GaAs quantum dots clearly show the interplay between radiative recombination and thermalization processes. In particular from temperature dependent PL spectra, we prove that the carrier recombination dynamics is ruled by the thermal population in optically inactive exciton states, related to the population of the first excited hole levels. Moreover time‐resolved spectra do not show any relaxation bottleneck, indicating an efficient carrier capture and a fast energy relaxation of the photogenerated carriers. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effects of thermal emission and re-trapping of photo-injected carriers on the optical transitions of InAs/GaAs quantum dots

“…2b). Thus, the thermal quenching of the FES transition can be explained by the thermal emission of carriers from the first excited state towards the second excited state of the dots that act as nonradiative levels (dark excited states) [15,17 ].…”

“…4c), the constant variation of the IPLI S suggests that the thermal escape of carriers was compensated by some mechanism providing carriers to the transitions. However, the mechanisms describing a redistribution of carriers between the excited states and the GS of the dots (intra-dot carrier redistribution mechanism) could be considered in the present case since the FES is believed to populate the DES via thermal escape of carriers [15][16][17]. On the other hand, Fig.…”

“…The thermal redistribution of carriers in this QD structure could result from the thermal release of excitons trapped in narrowing potentials [9,10] and also from the thermal transport of carriers from the ground states of small QDs into lower-lying states of larger dots [11][12][13][14]. However, only a few works have reported carrier exchange mechanisms between the excited states and the GS of the QDs from temperaturedependent PL investigations [15][16][17]. In reference [15], Levesque et al have shown from yhe optical study of vertically aligned InAs/InP QDs that the first excited states could be repopulated via a thermal escape of carriers coming from the ground states.…”