  Single photon emitters (SPEs) hosted in hexagonal boron nitride (hBN) are
essential elementary building blocks for enabling future on-chip quantum
photonic technologies that operate at room temperature. However, fundamental
challenges, such as managing non-radiative decay, competing incoherent
processes, as well as engineering difficulties in achieving deterministic
placement and scaling of the emitters, limit their full potential. In this
work, we experimentally demonstrate large-area arrays of plasmonic
nanoresonators for Purcell-induced site-controlled SPEs by engineering
emitter-cavity coupling and enhancing radiative emission at room temperature.
The plasmonic nanoresonator architecture consists of gold-coated silicon
pillars capped with an alumina spacer layer, enabling a 10-fold local field
enhancement in the emission band of native hBN defects. Confocal
photoluminescence and second-order autocorrelation measurements show bright
SPEs with sub-30 meV bandwidth and a saturated emission rate of more than 3.8
million counts per second. We measure a Purcell factor of 4.9, enabling average
SPE lifetimes of 480 ps, a five-fold reduction as compared to emission from
gold-free devices, along with an overall SPE yield of 21%. Density functional
theory calculations further reveal the beneficial role of an alumina spacer
between defected hBN and gold, as an insulating layer can mitigate the
electronic broadening of emission from defects proximal to gold. Our results
offer arrays of bright, heterogeneously integrated quantum light sources,
paving the way for robust and scalable quantum information systems.
