Decay dynamics and exciton localization in large GaAs quantum dots grown by droplet epitaxy

Title
Decay dynamics and exciton localization in large GaAs quantum dots grown by droplet epitaxy
Authors
P. TighineanuR. Daveau이은혜송진동S. StobbeP. Lodahl
Keywords
GaAs; droplet; Quantum efficiency
Issue Date
2013-10
Publisher
Physical review B, Condensed matter and materials physics
Citation
VOL 88, NO 15, 155320-1-155320-13
Abstract
We investigate the optical emission and decay dynamics of excitons confined in large strain-free GaAs quantum dots grown by droplet epitaxy. From time-resolved measurements combined with a theoretical model we show that droplet-epitaxy quantum dots have a quantum efficiency of about 75% and an oscillator strength between 8 and 10. The quantum dots are found to be fully described by a model for strongly confined excitons, in contrast to the theoretical prediction that excitons in large quantum dots exhibit the so-called giant oscillator strength.We attribute these findings to localized ground-state excitons in potential minima created by material intermixing during growth. We provide further evidence for the strong-confinement regime of excitons by extracting the size of electron and hole wave functions from the phonon-broadened photoluminescence spectra. Furthermore, we explore the temperature dependence of the decay dynamics and, for some quantum dots, observe a pronounced reduction in the effective transition strength with temperature. We quantify and explain these effects as being an intrinsic property of large quantum dots owing to thermal excitation of the ground-state exciton. Our results provide a detailed understanding of the optical properties of large quantum dots in general, and of quantum dots grown by droplet epitaxy in particular.
URI
http://pubs.kist.re.kr/handle/201004/46626
ISSN
10980121
Appears in Collections:
KIST Publication > Article
Files in This Item:
There are no files associated with this item.
Export
RIS (EndNote)
XLS (Excel)
XML


qrcode

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

BROWSE