Scalable site-controlled activation of emitters in locally strained few-layer hexagonal boron nitride

Point defects in hexagonal boron nitride (hBN) offer promising routes toward engineering single photon emitters crucial for the next-generation photonic technologies, including quantum communication, optical quantum computing, and quantum sensing. However, such integrated quantum architectures face challenges in realizing scalable approaches for the deterministic positioning of hBN emitter arrays. Though progress has been made in such on-demand generation, their low quantum efficiency in terms of yield, photoluminescence, and compromised coherence hinders their practical applications. Here, we demonstrate a large-scale site-controlled activation of hBN emitters with a near-unity emitter creation probability by utilizing a plasmonic nanopillar architecture with the highest aspect ratio reported to date to induce a conformal nanoscale-strain perturbation that locally modifies the electronic band structure of multilayered hBN leading to the generation of optically active defect centers. Confocal PL mapping at room temperature shows, for the first time in hBN, near 100% site-controlled activation of emitters with an ultrasharp emission peak around 695 nm having an FWHM of ~7 meV along with 52-fold radiative enhancement compared to non-PNP emitters. Our results establish a scalable and high throughput process with the potential for engineering an optoelectronic heterogeneous integration platform for their applications in on-chip quantum technologies.