Plasmonic Brightening of Room-temperature Single-Photon Emitters in Hexagonal Boron Nitride

Quantum emitters hosted on hexagonal boron nitride (hBN) surfaces provide opportunities to control their spin-optical properties. However, untreated hBN exhibits low photoluminescence (PL) quantum yield (QY), primarily due to structural defects and impurities. Additionally, the high binding energy of Frenkel-type excitons in hBN contributes to the low PL QY, as it makes the recombination process less efficient. To brighten the single photon emissions from hBN films, various strategies have been employed. Here, we report plasmonic-enhanced quantum emitters in hBN by controlled thermal annealing. Among four observed quantum emitters with energies of 1.83, 2.13, 1.75, and 1.95 eV, the emitter with energy of 1.95 eV demonstrates the room temperature heralded single photon criterion with zero-delay second-order autocorrelation of g(2)(0) = 0.44 < 0.5. Importantly, the PL QY of the hBN quantum emitters is plasmonically controlled, resulting in an increase in radiative recombination through a Purcell enhancement factor of 160%. The ability to operate hBN quantum emitters at room temperature with enhanced photoluminescence quantum yield will be transformative for their integration into quantum photonic circuitry.