Defects in hexagonal boron nitride (hBN) exhibit high-brightness, room-temperature quantum emission, but their large spectral variability and unknown local structure challenge their technological utility. Here, we directly correlate hBN quantum emission with local strain using a combination of photoluminescence (PL), cathodoluminescence (CL) and nanobeam electron diffraction. Across 40 emitters, we observe zero phonon lines (ZPLs) in PL and CL ranging from 540 to 720 nm. CL mapping reveals that multiple defects and distinct defect species located within an optically diffraction-limited region can each contribute to the observed PL spectra. Local strain maps indicate that strain is not required to activate the emitters and is not solely responsible for the observed ZPL spectral range. Instead, at least four distinct defect classes are responsible for the observed emission range, and all four classes are stable upon both optical and electron illumination. Our results provide a foundation for future atomic-scale optical characterization of colour centres.
Subscribe to Journal
Get full journal access for 1 year
only $17.42 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
All strain analysis data presented in Fig. 5 are included in Supplementary Information. Due to large file sizes, strain mapping and all other electron microscopy source data are available from the corresponding authors on request.
Kucsko, G. et al. Nanometre-scale thermometry in a living cell. Nature 500, 54–58 (2013).
Taylor, J. et al. High-sensitivity diamond magnetometer with nanoscale resolution. Nat. Phys. 4, 810–816 (2008).
Aslam, N. et al. Nanoscale nuclear magnetic resonance with chemical resolution. Science 357, 67–71 (2017).
Wehner, S., Elkouss, D. & Hanson, R. Quantum internet: a vision for the road ahead. Science 362, eaam9288 (2018).
Liao, S.-K. et al. Satellite-to-ground quantum key distribution. Nature 549, 43–47 (2017).
Awschalom, D. D., Hanson, R., Wrachtrup, J. & Zhou, B. B. Quantum technologies with optically interfaced solid-state spins. Nat. Photonics 12, 516–527 (2018).
Atatüre, M., Englund, D., Vamivakas, N., Lee, S.-Y. & Wrachtrup, J. Material platforms for spin-based photonic quantum technologies. Nat. Rev. Mater. 3, 38–51 (2018).
Tran, T. T., Bray, K., Ford, M. J., Toth, M. & Aharonovich, I. Quantum emission from hexagonal boron nitride monolayers. Nat. Nanotechnol. 11, 37–41 (2016).
Jungwirth, N. R. et al. Temperature dependence of wavelength selectable zero-phonon emission from single defects in hexagonal boron nitride. Nano Letters 16, 6052–6057 (2016).
Grosso, G. et al. Tunable and high-purity room temperature single-photon emission from atomic defects in hexagonal boron nitride. Nat. Commun. 8, 705 (2017).
Sontheimer, B. et al. Photodynamics of quantum emitters in hexagonal boron nitride revealed by low-temperature spectroscopy. Phys. Rev. B 96, 121202 (2017).
Exarhos, A. L., Hopper, D. A., Grote, R. R., Alkauskas, A. & Bassett, L. C. Optical signatures of quantum emitters in suspended hexagonal boron nitride. ACS Nano 11, 3328–3336 (2017).
Martínez, L. et al. Efficient single photon emission from a high-purity hexagonal boron nitride crystal. Phys. Rev. B 94, 121405 (2016).
Tran, T. T. et al. Robust multicolor single photon emission from point defects in hexagonal boron nitride. ACS Nano 10, 7331–7338 (2016).
Choi, S. et al. Engineering and localization of quantum emitters in large hexagonal boron nitride layers. ACS Appl. Mater. Interfaces 8, 29642–29648 (2016).
Chejanovsky, N. et al. Structural attributes and photodynamics of visible spectrum quantum emitters in hexagonal boron nitride. Nano Lett. 16, 7037–7045 (2016).
Jungwirth, N. R. & Fuchs, G. D. Optical absorption and emission mechanisms of single defects in hexagonal boron nitride. Phys. Rev. Lett. 119, 057401 (2017).
Schell, A. W., Svedendahl, M. & Quidant, R. Quantum emitters in hexagonal boron nitride have spectrally tunable quantum efficiency. Adv. Mater. 30, 1704237 (2018).
Reimers, J. R., Sajid, A., Kobayashi, R. & Ford, M. J. Understanding and calibrating density-functional-theory calculations describing the energy and spectroscopy of defect sites in hexagonal boron nitride. J. Chem. Theory Comput. 14, 1602–1613 (2018).
Tawfik, S. A. et al. First-principles investigation of quantum emission from hBN defects. Nanoscale 9, 13575–13582 (2017).
Feng, J. et al. Imaging of optically active defects with nanometer resolution. Nano Lett. 18, 1739–1744 (2018).
Bourrellier, R. et al. Bright uv single photon emission at point defects in h-bn. Nano Lett. 16, 4317–4321 (2016).
Meuret, S. et al. Photon bunching in cathodoluminescence. Phys. Rev. Lett. 114, 197401 (2015).
Alem, N. et al. Atomically thin hexagonal boron nitride probed by ultrahigh-resolution transmission electron microscopy. Phys. Rev. B 80, 155425 (2009).
Jin, C., Lin, F., Suenaga, K. & Iijima, S. Fabrication of a freestanding boron nitride single layer and its defect assignments. Phys. Rev. Lett. 102, 195505 (2009).
Wong, D. et al. Characterization and manipulation of individual defects in insulating hexagonal boron nitride using scanning tunnelling microscopy. Nat. Nanotechnol. 10, 949–953 (2015).
Lin, W.-H. et al. Atomic-scale structural and chemical characterization of hexagonal boron nitride layers synthesized at the wafer-scale with monolayer thickness control. Chem. Mater. 29, 4700–4707 (2017).
Barja, S. et al. Identifying substitutional oxygen as a prolific point defect in monolayer transition metal dichalcogenides. Nat. Commun. 10, 3382 (2019).
Cassabois, G., Valvin, P. & Gil, B. Hexagonal boron nitride is an indirect bandgap semiconductor. Nat. Photonics 10, 262–266 (2016).
Koperski, M., Nogajewski, K. & Potemski, M. Single photon emitters in boron nitride: more than a supplementary material. Opt. Commun. 411, 158–165 (2018).
de la Peña, F. et al. hyperspy/hyperspy v.1.4.1 (Zenodo, 2018); https://doi.org/10.5281/zenodo.1469364.
Katzir, A., Suss, J., Zunger, A. & Halperin, A. Point defects in hexagonal boron nitride. I. EPR, thermoluminescence, and thermally-stimulated-current measurements. Phys. Rev. B 11, 2370 (1975).
Xue, Y. et al. Anomalous pressure characteristics of defects in hexagonal boron nitride flakes. ACS Nano 12, 7127–7133 (2018).
Vogl, T., Doherty, M. W., Buchler, B. C., Lu, Y. & Lam, P. K. Atomic localization of quantum emitters in multilayer hexagonal boron nitride. Nanoscale 11, 14362–14371 (2019).
Kotakoski, J., Jin, C., Lehtinen, O., Suenaga, K. & Krasheninnikov, A. Electron knock-on damage in hexagonal boron nitride monolayers. Phys. Rev. B 82, 113404 (2010).
Meyer, J. C., Chuvilin, A., Algara-Siller, G., Biskupek, J. & Kaiser, U. Selective sputtering and atomic resolution imaging of atomically thin boron nitride membranes. Nano Lett. 9, 2683–2689 (2009).
Weston, L., Wickramaratne, D., Mackoit, M., Alkauskas, A. & Van de Walle, C. G. Native point defects and impurities in hexagonal boron nitride. Phys. Rev. B 97, 214104 (2018).
Yin, L.-C., Cheng, H.-M. & Saito, R. Triangle defect states of hexagonal boron nitride atomic layer: density functional theory calculations. Phys. Rev. B 81, 153407 (2010).
The authors acknowledge useful discussions about strain mapping with T. Pekin (Humboldt-Universität zu Berlin) and about CL–PL correlations with C. McLellan (Stanford). TEM imaging and spectroscopy were performed at the Stanford Nano Shared Facilities and Stanford Soft & Hybrid Materials Facility. The PL, TEM experiments and theoretical modelling were supported by the DOE ‘Photonics at Thermodynamic Limits’ Energy Frontier Research Center under grant no. DE-SC0019140. F.H. gratefully acknowledges the support of the Diversifying Academia, Recruiting Excellence (DARE) Doctoral Fellowship Program by Stanford University. J.V. acknowledges the support the NSF Quantum Leap EAGER grant no. DMR 1838380. T.F.H. and L.Y. also acknowledge support from the Betty and Gordon Moore Foundation EPiQS Initiative through grant no. GBMF4545.
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
a, HAADF and decomposed CL spectral weight maps of the emitter with ZPL at 578 nm in Fig. 4a of main text. b, CL spectral components showing higher energy peaks similar to that in Fig. 2a. c, HAADF and CL spectral weight maps of the emitter E6 in Fig. 3a with ZPL at 590 nm. d, CL spectral components for emitter in (c). Each pixel in the CL weight maps is 15 nm. For both emitters here, the PL spectrum has two probable phonon-sidebands, a similar spectral signature to the emitter in the main text Fig. 2a. All these three emitters have four higher energy (UV-blue) peaks in their CL spectrum. For the particular emitter in panels (c-d), spectral decomposition shows that the 420 nm emitter is located 80 nm away from the 590 nm emitter. However, the 460 nm, 500 nm and 532 nm peaks are localized to the same 15 nm bright pixel as the 590 nm peak.
About this article
Cite this article
Hayee, F., Yu, L., Zhang, J.L. et al. Revealing multiple classes of stable quantum emitters in hexagonal boron nitride with correlated optical and electron microscopy. Nat. Mater. 19, 534–539 (2020). https://doi.org/10.1038/s41563-020-0616-9