Figure 2: Gate-dependent spectral properties of NV centres.

(a) Spectra of the H-terminated area of a 10 keV implantation in a region with high implantation density (black: U_G=+0.5 V, red: U_G=−0.5 V). ZPL, zero-phonon-line. (b–d) Difference of the spectra at U_G=+0.5 V and U_G=−0.5 V ((b) at ∼10¹³ cm⁻², (c) at ∼10¹² cm⁻² and (d) at ∼10¹¹ cm⁻²). The dashed line indicates zero level. (e) Difference spectrum of a single NV centre (implantation density ∼10¹¹ cm⁻²) when switching from U_G=+0.4 V to U_G=−0.4 V. The dashed line indicates zero level.