Spectroscopy of photoionization from the ${}^{1}E$ singlet state in nitrogen$-$vacancy centers in diamond

Abstract

The ${}^{1}E{-}^1{A}_1$ singlet manifold of the negatively charged nitrogen vacancy $(N{V}^{-})$ center in diamond plays a central role in the quantum information and quantum sensing applications of the $N{V}^{-}$ center. However, the energy of this manifold within the diamond bandgap and with respect to the ${}^3{A}_2{-}^{3}E$ triplet manifold has not been measured directly. Using field-quenching effects on photoluminescence (PL) spectra, we report on the energy gap between the ${}^{1}E{-}^1{A}_1$ singlet manifold and the ${}^3{A}_2$ and ${}^{3}E$ ground and excited triplet states of the $N{V}^{-}$ as a function of excitation wavelength and power, temperature, and applied magnetic field in a heavily nitrogen-doped sample. Increased PL and decreased zero-phonon line width from the $N{V}^0$ were observed in the presence of an applied magnetic field, indicating ionization from the long-lived ${}^{1}E$ singlet state. A temperature-dependent ionization threshold between 532 nm and 550 nm was found, locating the singlet states within the diamond band gap.

arXiv comment10 pages, 7 figures. Submission to Physical Review B