  Creating single photons in the telecommunication wavelength range from
semiconductor quantum dots (QDs) and interfacing them with spins of electrons
or holes has been of high interest in recent years, with research mainly
focusing on indium based QDs. However, there is not much data on the optical
and spin properties of galliumantimonide (GaSb) QDs, despite it being a
physically rich system with an indirect to direct bandgap crossover in the
telecom wavelength range. Here, we investigate the (quantum-) optical
properties of GaSb quantum dots, which are fabricated by filling droplet-etched
nanoholes in an aluminum-galliumantimonide (AlGaSb) matrix. We observe
photoluminescence (PL) features from isolated and highly symmetric QDs that
exhibit narrow linewidth in the telecom S-band and show an excitonic fine
structure splitting of $\Delta E=(12.0\pm0.5)\mu eV$. Moreover, we perform
time-resolved measurements of the decay characteristics of an exciton and
measure the second-order photon autocorrelation function of the charge complex
to $g^{(2)}(0)=0.16\pm0.02$, revealing clear antibunching and thus proving the
capability of this material platform to generate non-classical light.
