  Nanoscale strain control of exciton funneling is an increasingly critical
tool for the scalable production of single photon emitters (SPEs) in
two-dimensional materials. However, conventional far-field optical microscopies
remain constrained in spatial resolution by the diffraction limit and thus can
only provide a limited description of nanoscale strain localization of SPEs.
Here, we quantify the effects of nanoscale heterogeneous strain on the energy
and brightness of GaSe SPEs on nanopillars with correlative
cathodoluminescence, photoluminescence, and atomic force microscopies supported
by density functional theory simulations. We report the strain-localized SPEs
have a broad range of emission wavelengths from 620 nm to 900 nm. We reveal
substantial strain-controlled SPE wavelength tunability over a ~ 100 nm
spectral range and two-orders of magnitude enhancement in the SPE brightness at
the pillar center due to Type-I exciton funneling. In addition, we show that
radiative biexciton cascade processes contribute to the observed CL photon
superbunching. Also, the measured GaSe SPE photophysics after electron beam
exposure shows the excellent stability of these SPEs. We anticipate this
insight into nanoscale strain control of two-dimensional SPEs will guide the
development of truly deterministic quantum photonics.

Optics;Materials Science