Bandgap tuning and single-photon emitters in III-V dilute nitrides nanowires through hydrogenation

Developing a finely energy-tunable solid-state single-photon source is a major challenge in the field of quantum communication and computation, and bandgap engineering at the nanoscale is a very promising, though challenging, solution to this issue. In this work, we have used GaAs/GaAsN core/multi-shell nanowires (NWs), with N content of 0.7% to 3%. N is the smallest among the other group V elements and has higher electronegativity, hence the incorporation of such a low concentration of N in GaAs creates a strong localized field in the host GaAs that results in a large and counterintuitive bandgap reduction up to ≈480 meV for N=3%. By using micro-photoluminescence (PL) spectroscopy, we demonstrate how the post-growth irradiation of H-ions tunes the bandgap of single GaAs/GaAsN NWs on a large energy scale. Treatment with H-ion creates indeed an N-H defect complex, which eliminates the perturbations induced by N incorporation in the GaAs lattice; therefore, we can practically tune the bandgap of GaAsN up to the value of GaAs. Through the subsequent thermal annealing of the wires, we have liberated the H from the N-H complex defect and partially or completely (depending on the desired bandgap energy) restored the effects of N incorporation in the GaAs lattice. This proves the positive degree of reversibility of this approach. By exploiting this, low temperature (5K) PL measurements of partially hydrogenated wires show single photon emission behavior, assessed by autocorrelation measurements (g(2)(0)). The source of single photon emission is identified as clusters of a few N atoms in the GaAs lattice. This process can be engineered by irradiating H-ions to achieve the tunability of single photon emission. The overall results suggest a promising route for creating an energy-controlled single photon emitter, fully integrated with a Si photonic chip.