  III-nitride quantum dots (QDs) are a promising system actively studied for
their ability to maintain single photon emission up to room temperature. Here,
we report on the evolution of the emission properties of self-assembled GaN/AlN
QDs for temperatures ranging from 5 to 300K. We carefully track the
photoluminescence of a single QD and measure an optimum single photon purity of
g(2)(0) = 0.05+-0.02 at 5 K and 0.17+-0.8 at 300 K. We complement this study
with temperaturedependent time-resolved photoluminescence measurements (TRPL)
performed on a QD ensemble to further investigate the exciton recombination
dynamics of such polar zero-dimensional nanostructures. By comparing our
results to past reports, we emphasize the complexity of recombination processes
in this system. Instead of the more conventional mono-exponential decay typical
of exciton recombination, TRPL transients display a bi-exponential feature with
short- and long-lived components that persist in the low excitation regime.
From the temperature insensitivity of the long-lived excitonic component, we
first discard the interplay of dark-to-bright state refilling in the exciton
recombination process. Besides, this temperature-invariance also highlights the
absence of nonradiative exciton recombinations, a likely direct consequence of
the strong carrier confinement observed in GaN/AlN QDs up to 300K. Overall, our
results support the viability of these dots as a potential single-photon source
for quantum applications at room temperature.
