Remote plasma for damage-controlled fabrication of single-photon emitters in ultrathin hexagonal boron nitride

Hexagonal boron nitride (hBN) hosts bright and robust color centers, with emission in the ultraviolet to near-infrared range, that are generally obtained either by activating pre-existing atomic defects or by purposefully introducing strain, vacancies, or impurities. Controlled fabrication remains a challenge as color centers often form on extended structural defects, including pre-existing flake edges, holes, and folds, as well as unintended damage sites created during vacancy generation. Here, we introduce a remote argon plasma technique to produce vacancies while minimizing material damage. Additionally, by independently tuning the ion flux and energy, we engineer large arrays of single-photon emitters (SPEs). Critically, the SPEs form away from nanoscale non-uniformities, in pristine flake regions. Our processing approach thus enables the formation of stable SPEs with bulk properties in atomically thin hBN. The noninvasive formation of color centers in 2D materials opens multiple pathways toward their applications in sensing and quantum photonics.