Activated single photon emitters and enhanced deep-level emissions in hexagonal boron nitride strain crystal

The peculiar defect-related photon emission processes in 2D hexagonal boron nitride (hBN) have become a topic of intense research due to their potential applications in quantum information and sensing technologies. Here, it is reported on exotic single photons and enhanced deep-level emissions in 2D hBN strain crystal, which is fabricated by transferring multilayer hBN onto hexagonal close-packed silica spheres on a silica substrate. Effective activation of single photon emission is realized from the defect ensembles in the multilayer hBN at positions that are in contact with the apex of the SiO${}_2$ spheres. At these points, the local tensile strain-induced overall blue shift of the SPE ensembles is up to 12 nm. Furthermore, high spatial resolution cathodoluminescence measurements show remarkable strain-enhanced deep-level emissions in the multilayer hBN with the emission intensity distribution following the periodic hexagonal pattern of the strain crystal. The maximum deep-level emission enhancement is up to 350% with an energy redshift of 6 nm. These results provide a simple on-chip compatible method for activating and tuning the defect-related photon emissions in multilayer hBN, demonstrating the potential of hBN strain crystal as a building block for future on-chip quantum nanophotonic devices. (© 2023 Wiley‐VCH GmbH)