  The realization of reliable single photon emitters operating at high
temperature and located at predetermined positions still presents a major
challenge for the development of solid-state systems for quantum light
applications. We demonstrate single-photon emission from two-dimensional
ordered arrays of GaN nanowires containing InGaN nano-disks. The structures
were fabricated by molecular beam epitaxy on (0001) GaN-on-sapphire templates
patterned with nanohole masks prepared by colloidal lithography.
Low-temperature cathodoluminescence measurements reveal the spatial
distribution of light emitted from a single nanowire heterostructure. The
emission originating from the topmost part of the InGaN regions covers the
blue-to-green spectral range and shows intense and narrow quantum dot-like
photoluminescence lines. These lines exhibit an average linear polarization
ratio of 92%. Photon correlation measurements show photon antibunching with a
g(2)(0) values well below the 0.5 threshold for single photon emission. The
antibunching rate increases linearly with the optical excitation power,
extrapolating to the exciton decay rate of ~1 ns-1 at vanishing pump power.
This value is comparable with the exciton lifetime measured by time-resolved
photoluminescence. Fast and efficient single photon emitters with controlled
spatial position and strong linear polarization are an important step towards
high-speed on-chip quantum information management.
