Stability of Near-Surface Nitrogen Vacancy Centers Using Dielectric Surface Passivation

Ravi Kumar; Saksham Mahajan; Felix Donaldson; Siddharth Dhomkar; Hector J Lancaster; Curran Kalha; Aysha A Riaz; Yujiang Zhu; Christopher A Howard; Anna Regoutz; John J L Morton

doi:10.1021/acsphotonics.3c01773

Stability of Near-Surface Nitrogen Vacancy Centers Using Dielectric Surface Passivation

ACS Photonics. 2024 Feb 14;11(3):1244-1251. doi: 10.1021/acsphotonics.3c01773. eCollection 2024 Mar 20.

Authors

Ravi Kumar¹, Saksham Mahajan², Felix Donaldson¹, Siddharth Dhomkar^{1

3

4}, Hector J Lancaster⁵, Curran Kalha⁶, Aysha A Riaz⁶, Yujiang Zhu⁶, Christopher A Howard⁵, Anna Regoutz⁶, John J L Morton^{1

2}

Affiliations

¹ London Centre for Nanotechnology, UCL, London WC1H 0AH, U.K.
² Department of Electronic & Electrical Engineering, UCL, London WC1E 7JE, U.K.
³ Department of Physics, IIT Madras, Chennai 600036, India.
⁴ Center for Quantum Information, Communication and Computing, IIT Madras, Chennai 600036, India.
⁵ Department of Physics and Astronomy, UCL, London WC1E 6BT, U.K.
⁶ Department of Chemistry, UCL, 20 Gordon Street, London WC1H 0AJ, U.K.

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.