  Impurity-bound excitons in ZnSe quantum wells are bright single photon
emitters--a crucial element in photonics-based quantum technology. But to
achieve the efficiencies required for practical applications, these emitters
must be integrated into optical cavities that enhance their radiative
properties and far-field emission pattern. In this work, we demonstrate
cavity-enhanced emission from a single impurity-bound exciton in a ZnSe quantum
well. We utilize a bullseye cavity structure optimized to feature a small mode
volume and a nearly Gaussian far-field transverse mode that can efficiently
couple to an optical fiber. The fabricated device displays emission that is
more than an order of magnitude brighter than bulk impurity-bound exciton
emitters in the ZnSe quantum well, as-well-as clear anti-bunching, which
verifies the single photon emission from the source. Time-resolved
photoluminescence spectroscopy reveals a Purcell-enhanced radiative decay
process with a Purcell factor of 1.43. This work paves the way towards high
efficiency spin-photon interfaces using an impurity-doped II-VI semiconductor
coupled to nanophotonics.
