Bandgap tuning and single-photon emitters in 3-5 dilute nitrides nanowires through hydrogenation

Semiconductor nanowires (NWs) are structures with optical and electronic properties due to their peculiar morphology. In this work, we demonstrated bandgap tuning on GaAs/GaAsN core/shell nanowires by post-growth hydrogenation. The passivating effect of hydrogen on nitrogen results in the restoration of the emission at the gap energy of GaAs. Subsequently, we subjected the wires to thermal annealing procedures to remove the hydrogen and thus restore the effect of nitrogen on the bandgap: a huge red-shift is observed, up to $200meV$, depending on the initial N concentration, leading to a degree of reversibility of the process. We achieved fine-tuning of the emission energy between hydrogenated and pristine NW states by controlling annealing parameters, such as temperature and duration. In addition, we observed single-photon light emission from single NWs. Optical measurements at 5K showed excitonic lines, arising from the non-hydrogenated N clusters with a g(2)(0)=0.32. These results are the basis for combining post-growth energy gap fine-tuning with single photon emission in NWs, to create an energy-controlled and site-controlled single photon emitter.