Identifying Luminescent Boron Vacancies in h-BN Generated Using Controlled He + Ion Irradiation.

The defect emission from h-BN at 1.55 eV is interesting as it enables optical readout of spins. It is necessary to identify the nature of the relevant point-of-defect for its controlled introduction. However, it is challenging to engineer point defects in h-BN without changing the local atomic structure. Here, we controllably introduce boron vacancies in h-BN using an ultrahigh spatial resolution and low-energy He + ion beam. By optimizing the He + ion irradiation conditions, we control the quantity and location of defects spatially and along the depth of h-BN to achieve a robust photoluminescence emission at 1.55 eV from 10 K to room temperature. We show that as-generated defects activate an additional Raman mode at 1295 cm -1 . Electron energy loss spectroscopy confirms introduction of boron vacancies without modification of the local h-BN crystal structure. Our results provide a deterministic strategy to create scalable boron vacancy emitters in h-BN for quantum photonics.