Identifying carbon as the source of visible single-photon emission from hexagonal boron nitride

Single-photon emitters (SPEs) in hexagonal boron nitride (hBN) have garnered increasing attention over the last few years due to their superior optical properties. However, despite the vast range of experimental results and theoretical calculations, the defect structure responsible for the observed emission has remained elusive. Here, by controlling the incorporation of impurities into hBN via various bottom-up synthesis methods and directly through ion implantation, we provide direct evidence that the visible SPEs are carbon related. Room-temperature optically detected magnetic resonance is demonstrated on ensembles of these defects. We perform ion-implantation experiments and confirm that only carbon implantation creates SPEs in the visible spectral range. Computational analysis of the simplest 12 carbon-containing defect species suggest the negatively charged VBC−N defect as a viable candidate and predict that out-of-plane deformations make the defect environmentally sensitive. Our results resolve a long-standing debate about the origin of single emitters at the visible range in hBN and will be key to the deterministic engineering of these defects for quantum photonic devices.This work at Nottingham was supported by the Engineering and Physical Sciences Research Council (grant numbers EP/K040243/1, EP/P019080/1). We also thank the University of Nottingham Propulsion Futures Beacon for funding towards this research. We also acknowledge financial support from the Australian Research Council (via DP180100077, DE180100810, DP160104621 and DP190101058, CECE200100010) and the Asian Office of Aerospace Research & Development (FA9550-19-S-0003). Access to the epitaxial growth facilities is made possible through the Australian National Fabrication Facility, ACT Node. Ion implantation was performed at the Australian Facility for Advanced Ion Implantation Research (AFAiiR), RSP (ANU). This work was supported in part by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division under contract number DE-AC02-05-CH11231, within the sp2 -Bonded Materials Program (KC2207), which provided for synthesis and structural characterization of hBN converted from carbon. The computational work was supported by National Computational Infrastructure (NCI), Intersect, the Shanghai University ICQMS high-performance computing facility and Chinese National Natural Science Foundation grant number 11674212. This work was supported in part by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy–EXC2147 ‘ct.qmat’ (project id 390858490)