Enhanced photon emission from site- and energy-controlled InGaAs/GaAs quantum dots coupled to GaAs nanowires

• InGaAs QDs grown in pyramidal pits are excellent single-photon sources. • However, they suffer from low photon extraction efficiency. • Growing GaAs nanowire antennas above them improves efficiency by up to x36. • This improvement is related to Purcell effect and increased acceptance angle. InGaAs/GaAs quantum dots (QDs) embedded in a GaAs substrate are very useful photon sources, including single and entangled photons, due to their unperturbed environment. Contrary to self-formed QDs, those grown in pyramidal pits can be well controlled in position and energy, important properties for scaling. However, photon extraction efficiency from these QDs is limited due to the GaAs/Air index mismatch and non-directionality of the emission. GaAs nanowires grown vertically on top of these QDs can serve as resonant antennas, thus enhancing their emission and increasing their usefulness as sources. Such structures were fabricated and their photon emission was studied by micro-photoluminescence as function of excitation power and temperature. The structures showed an intensity increase by up to x36 over quantum dots without nanowire antennas.