Efficient Electrical Spin Readout of ${\mathrm{NV}}^{-}$ Centers in Diamond

Using pulsed photoionization the coherent spin manipulation and echo formation of ensembles of ${\mathrm{NV}}^{-}$ centers in diamond are detected electrically, realizing contrasts of up to 17%. The underlying spin-dependent ionization dynamics are investigated experimentally and compared to Monte Carlo simulations. This allows the identification of the conditions optimizing contrast and sensitivity, which compare favorably with respect to optical detection.

Figure 1

(a) Spin-dependent photoionization of ${\mathrm{NV}}^{-}$ centers used for the electrical readout of their spin states. (b) Schematic drawing of the sample and the measurement setup. (c) Level scheme used for the Monte Carlo simulation.

Figure 2

(a) Pulsed electrically detected magnetic resonance spectrum for $B_0\parallel ⟨111⟩$. Measurement time: two minutes. (b) Rabi oscillations in the contrast $\mathrm{\Delta }I/I$ (symbols) with a fit of an exponentially decaying cosine (line). The inset shows the frequency of the Rabi oscillations (symbols) measured at different microwave powers and a linear fit (line). (c) Spin echo measurement (symbols) with a fit of a Gaussian (line). (d) Echo decay measurement showing the first ESEEM decay. The pulse sequences used for the measurements are shown on top of the respective figure. $T_{\pi }$ is the length of a $\pi$ pulse.

Figure 3

(a) Contrast $\mathrm{\Delta }I/I$ for a $\pi$ microwave pulse as a function of the pulse length $T_{\mathrm{ion}}$ of the ionization pulse for different ionization pulse powers $P_{\mathrm{ion}}$. (b) $\mathrm{\Delta }I/I$ as a function of the pulse length $T_{\text{reset}}$ of an additional reset pulse for different reset pulse powers $P_{\text{reset}}$. The pulse sequence used is shown on top of the figure. (c) Photocurrent through the sample as a function of the laser power. The green line is a fit of a polynomial of degree 2; the red line is a fit of a linear function.

Figure 4

(a) Contrast $\mathrm{\Delta }I/I$ as a function of the length of the ionization pulse $T_{\mathrm{ion}}$ for three pulse powers taken from Fig. 3 and a simultaneous fit of a Monte Carlo simulation (black lines). (b) Simulated charge carrier generation rate $G_{|1⟩}$ and $G_{|2⟩}$ plotted as a function of the time during the ionization pulse $T_{\mathrm{ion}}$ for starting states $|1⟩$ and $|2⟩$, respectively. The black line depicts a constant background charge carrier generation rate $G_{{\mathrm{N}}_{\mathrm{s}}^0}$ originating from substitutional nitrogen donors. (c) Simulated $\mathrm{\Delta }I/I$ as function of $T_{\mathrm{ion}}$ for different $P_{\mathrm{ion}}$ under optimal conditions. (d) Sensitivity ${\eta }_{\mathrm{pEDMR}}$ as a function of $T_{\mathrm{ion}}$ for different $P_{\mathrm{ion}}$ under optimal conditions. ${\eta }_{\mathrm{ODMR}}$ marks the typical ODMR sensitivity.