  Single-photon emitters (SPEs) are at the basis of many applications for
quantum information management. Semiconductor-based SPEs are best suited for
practical implementations because of high design flexibility, scalability and
integration potential in practical devices. Single-photon emission from ordered
arrays of InGaN nano-disks embedded in GaN nanowires is reported. Intense and
narrow optical emission lines from quantum dot-like recombination centers are
observed in the blue-green spectral range. Characterization by electron
microscopy, cathodoluminescence and micro-photoluminescence indicate that
single photons are emitted from regions of high In concentration in the
nano-disks due to alloy composition fluctuations. Single-photon emission is
determined by photon correlation measurements showing deep anti-bunching minima
in the second-order correlation function. The present results are a promising
step towards the realization of on-site/on-demand single-photon sources in the
blue-green spectral range operating in the GHz frequency range at high
temperatures.
