Deterministic single-photon sources in hexagonal boron nitride with electron-dose-tuned purity and reversible thermal quenching

Electron-beam irradiation is an established route to create site-controlled, room-temperature single-photon emitters (SPEs) in hexagonal boron nitride (hBN), but two aspects remain underexplored: how the electron dose governs the properties of the resulting single emitters, and how the emission behaves when the host is heated above room temperature. Here, we create emitters deterministically with a focused electron beam and confirm single-photon emission across three independent flakes, with $g^{(2)}(0)=0.09$, $0.12$, and $0.16$. We map the single-emitter response (yield, spectrum, lifetime, and photon purity) as a function of electron dose, identifying an optimal window for high-purity single emitters. Consistent with recent cryogenic studies, we assign the bright room-temperature feature near 575 n to the phonon sideband (PSB) of a green–yellow emitter whose zero-phonon line (ZPL) lies near 548 nm. Temperature-dependent photoluminescence measured in situ under real-time from room temperature to 300 degrees C reveals a thermal quenching that is fully reversible upon cooling, in contrast to the irreversible annealing-induced degradation reported elsewhere, indicating that transient heating does not permanently damage the centers. These results add quantitative dose control and above-room-temperature operation to the toolbox for deterministic hBN quantum-light sources.