Quantum dots on GaAs substrates as integration-ready high-performance single-photon sources at telecommunication wavelengths

The development of deterministic single-photon sources emitting in the telecommunication bands is a key challenge for quantum communication and photonic quantum computing. Here, we investigate the optical properties and single-photon emission of molecular beam epitaxy (MBE) grown semiconductor quantum dots (QDs) emitting in the telecom O- and C-bands. The QDs are embedded in an InGaAs matrix with fixed indium content grown on top of a compositionally graded InGaAs buffer. This structure allows for the future implementation of electrically contacted nanocavities to enable high-quality and bright QD emission. In detailed optical characterizations we observe linewidths as low as 50 μeV, close to the spectrometer resolution limit, low fine structure splittings close to 10μeV, and g⁽²⁾(0) values as low as 0.08. These results advance the current performance metrics for MBE-grown QDs on GaAs substrates emitting in the telecom bands and showcase the potential of the heterostructures presented for further integration into photonic devices.