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Völker LA, Herb K, Merchant DA, Bechelli L, Degen CL, Abendroth JM. Charge and Spin Dynamics and Destabilization of Shallow Nitrogen-Vacancy Centers under UV and Blue Excitation. NANO LETTERS 2024; 24:11895-11903. [PMID: 39265047 DOI: 10.1021/acs.nanolett.4c03064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/14/2024]
Abstract
Shallow nitrogen-vacancy (NV) centers in diamond offer opportunities to study photochemical reactions, including photogeneration of radical pairs, at the single-molecule regime. A prerequisite is a detailed understanding of charge and spin dynamics of NVs exposed to the short-wavelength light required to excite chemical species. Here, we investigate the charge and spin dynamics of shallow NVs under 445 and 375 nm illumination. With blue excitation, charge-state preparation is power-dependent, and modest spin initialization fidelity is observed. Under UV excitation, charge-state preparation is power-independent and no spin polarization is observed. Aging of NVs under prolonged UV exposure manifests in a reduced charge stability and spin contrast. We attribute this aging to modified local charge environments of near-surface NVs and identify distinct electronic traps only accessible at short wavelengths. Finally, we evaluate the prospects of NVs to probe photogenerated radical pairs based on measured sensitivities and outline possible sensing schemes.
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Affiliation(s)
- Laura A Völker
- Department of Physics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - Konstantin Herb
- Department of Physics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - Darin A Merchant
- Department of Physics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - Lorenzo Bechelli
- Department of Physics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
| | - Christian L Degen
- Department of Physics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
- Quantum Center, ETH Zürich, 8093 Zürich, Switzerland
| | - John M Abendroth
- Department of Physics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland
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Kumar R, Mahajan S, Donaldson F, Dhomkar S, Lancaster HJ, Kalha C, Riaz AA, Zhu Y, Howard CA, Regoutz A, Morton JJL. Stability of Near-Surface Nitrogen Vacancy Centers Using Dielectric Surface Passivation. ACS PHOTONICS 2024; 11:1244-1251. [PMID: 38523744 PMCID: PMC10958592 DOI: 10.1021/acsphotonics.3c01773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 01/26/2024] [Accepted: 01/26/2024] [Indexed: 03/26/2024]
Abstract
We study the photophysical stability of ensemble near-surface nitrogen vacancy (NV) centers in diamond under vacuum and air. The optically detected magnetic resonance contrast of the NV centers was measured following exposure to laser illumination, showing opposing trends in air compared to vacuum (increasing by up to 9% and dropping by up to 25%, respectively). Characterization using X-ray photoelectron spectroscopy (XPS) suggests a surface reconstruction: In air, atmospheric oxygen adsorption on a surface leads to an increase in NV- fraction, whereas in vacuum, net oxygen desorption increases the NV0 fraction. NV charge state switching is confirmed by photoluminescence spectroscopy. Deposition of ∼2 nm alumina (Al2O3) over the diamond surface was shown to stabilize the NV charge state under illumination in either environment, attributed to a more stable surface electronegativity. The use of an alumina coating on diamond is therefore a promising approach to improve the resilience of NV sensors.
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Affiliation(s)
- Ravi Kumar
- London
Centre for Nanotechnology, UCL, London WC1H 0AH, U.K.
| | - Saksham Mahajan
- Department
of Electronic & Electrical Engineering, UCL, London WC1E 7JE, U.K.
| | - Felix Donaldson
- London
Centre for Nanotechnology, UCL, London WC1H 0AH, U.K.
| | - Siddharth Dhomkar
- London
Centre for Nanotechnology, UCL, London WC1H 0AH, U.K.
- Department
of Physics, IIT Madras, Chennai 600036, India
- Center for
Quantum Information, Communication and Computing, IIT Madras, Chennai 600036, India
| | | | - Curran Kalha
- Department
of Chemistry, UCL, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - Aysha A. Riaz
- Department
of Chemistry, UCL, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - Yujiang Zhu
- Department
of Chemistry, UCL, 20 Gordon Street, London WC1H 0AJ, U.K.
| | | | - Anna Regoutz
- Department
of Chemistry, UCL, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - John J. L. Morton
- London
Centre for Nanotechnology, UCL, London WC1H 0AH, U.K.
- Department
of Electronic & Electrical Engineering, UCL, London WC1E 7JE, U.K.
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Zhu Y, Yu VWZ, Galli G. First-Principles Investigation of Near-Surface Divacancies in Silicon Carbide. NANO LETTERS 2023; 23:11453-11460. [PMID: 38051297 DOI: 10.1021/acs.nanolett.3c02880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
The realization of quantum sensors using spin defects in semiconductors requires a thorough understanding of the physical properties of the defects in the proximity of surfaces. We report a study of the divacancy (VSiVC) in 3C-SiC, a promising material for quantum applications, as a function of surface reconstruction and termination with -H, -OH, -F and oxygen groups. We show that a VSiVC close to hydrogen-terminated (2 × 1) surfaces is a robust spin-defect with a triplet ground state and no surface states in the band gap and with small variations of many of its physical properties relative to the bulk, including the zero-phonon line and zero-field splitting. However, the Debye-Waller factor decreases in the vicinity of the surface and our calculations indicate it may be improved by strain-engineering. Overall our results show that the VSiVC close to SiC surfaces is a promising spin defect for quantum applications, similar to its bulk counterpart.
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Affiliation(s)
- Yizhi Zhu
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Victor Wen-Zhe Yu
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Giulia Galli
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
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