Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Decay dynamics and exciton localization in large GaAs quantum dots grown
  by droplet epitaxy   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 wavefunctions 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.

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The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc
21
The categories of this paper are: adap-org
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
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The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph