Systematic investigation of the generation of luminescent emitters in hBN via irradiation engineering.

Hexagonal boron nitride (hBN), a two-dimensional (2D) material, garners interest for hosting bright quantum emitters at room temperature. While crystallographic defects are widely believed to be the source of these emitters, their exact nature, especially for visible frequencies, remains debated. Carbon impurities are frequently implicated, though their precise role is unclear, and extrinsic organic molecules at the hBN-substrate interface have also been proposed as contributors. In this study, we systematically explore the formation of luminescent emitters through irradiation engineering. Our results confirm that low-energy oxygen irradiation followed by annealing is key to forming visible quantum emitters in hBN. Notably, post-annealing in carbon-rich atmospheres significantly increases emitter density, reinforcing carbon’s potential role. We also find that hBN crystallographic quality influences emitter generation, with low-quality hBN producing nearly 20 percent more emitters than high-quality samples. While the formation of extrinsic organic molecules during high-temperature annealing cannot be ruled out, crystallographic defects formed during irradiation are central to emitter creation. We infer that these defects may promote the formation of few-atom luminescent centers and serve as molecular pinning sites. Our systematic study and findings advance the understanding of the formation of visible frequency quantum emitters in hBN.