ABSTRACT Defect and impurity centers in diamond can exist in multiple charge states. A notable example is a negatively and neutrally charged nitrogen‐vacancy center in diamond, whose optical and spin properties are very different. Recent DFT studies show that an energetically favorable charge state can be controlled by adjusting the chemical potential of the diamond sample, which often requires significant materials engineering. This study presents an alternative approach for the control of charge states with the use of nanosecond high‐voltage pulse discharges. We demonstrate the control of silicon‐vacancy (SiV) centers in diamond. Using time‐resolved photoluminescence (PL) spectroscopy measurement of the SiV centers with the application of nanosecond high‐voltage pulses, we show the emergence of the negatively charged SiV − state. We also employ the time‐resolved PL measurements and show that the population of the induced SiV − charge state decays exponentially, and the lifetime of the charge state is determined by 200–1100 ms. The observed long‐lived charge state is potentially useful for applications based on the SiV − center. This method also paved the way to access various charge states of defect and impurity centers in diamond and wide‐bandgap semiconductors.
ABSTRACT Defect and impurity centers in diamond can exist in multiple charge states. A notable example is a negatively and neutrally charged nitrogen‐vacancy center in diamond, whose optical and spin properties are very different. Recent DFT studies show that an energetically favorable charge state can be controlled by adjusting the chemical potential of the diamond sample, which often requires significant materials engineering. This study presents an alternative approach for the control of charge states with the use of nanosecond high‐voltage pulse discharges. We demonstrate the control of silicon‐vacancy (SiV) centers in diamond. Using time‐resolved photoluminescence (PL) spectroscopy measurement of the SiV centers with the application of nanosecond high‐voltage pulses, we show the emergence of the negatively charged SiV − state. We also employ the time‐resolved PL measurements and show that the population of the induced SiV − charge state decays exponentially, and the lifetime of the charge state is determined by 200–1100 ms. The observed long‐lived charge state is potentially useful for applications based on the SiV − center. This method also paved the way to access various charge states of defect and impurity centers in diamond and wide‐bandgap semiconductors.
Abstract Nitrogen-vacancy (NV) and silicon-vacancy (SiV) color defects in diamond are promising systems for applications in quantum technology. The NV and SiV centers have multiple charge states, and their charge states have different electronic, optical and spin properties. For the NV centers, most investigations for quantum sensing applications are targeted on the negatively charged NV (NV−), and it is important for the NV centers to be in the NV− state. However, it is known that the NV centers are converted to the neutrally charged state (NV0) under laser excitation. An energetically favorable charge state for the NV and SiV centers depends on their local environments. It is essential to understand and control the charge state dynamics for their quantum applications. In this work, we discuss the charge state dynamics of NV and SiV centers under high-voltage nanosecond pulse discharges. The NV and SiV centers coexist in the diamond crystal. The high-voltage pulses enable manipulating the charge states efficiently. These voltage-induced changes in charge states are probed by their photoluminescence spectral analysis. The analysis result from the present experiment shows that the high-voltage nanosecond pulses cause shifts of the chemical potential and can convert the charge states of NV and SiV centers with the transition rates of ∼MHz. This result also indicates that the major population of the SiV centers in the sample is the doubly negatively charged state (SiV2−), which is often overlooked because of its non-fluorescent and non-magnetic nature. This demonstration paves a path for a method of rapid manipulation of the NV and SiV charge states in the future.
Silicon-vacancy defects have been identified as a promising optical transition for quantum communications, quantum control, and quantum information processing. In the work presented here, we demonstrate a voltage-controlled mechanism by which the photoluminescent (PL) emission from silicon-vacancy (Si-V) defects in diamond can be modulated. In particular, we can selectively produce emission from the negatively charged state of this defect (i.e., Si-V−), which exhibits narrow (Γ = 4 nm) emission at 738 nm at low laser power. This approach uses high voltage (2–5 kV) nanosecond pulses applied across top and bottom electrodes on a 0.5 mm thick diamond substrate. In the absence of high voltage pulses, we observe no emission at 738 nm. This feature increases monotonically with peak pulse voltage, pulse repetition rate (i.e., frequency), and incident laser intensity. We observe saturation of the PL intensity for pulse voltages above 3.2 kV and frequency above 100 Hz. Based on electrostatic simulations, we estimated the local electric field intensity near the tip of the Cu electrode to be 2.8 ×106 V/cm at these voltages. However, as a function of laser power, we observe a linear dependence of PL intensity without saturation. These saturating and non-saturating behaviors provide important insight into the voltage-induced charging mechanisms and kinetics associated with this process.
Silicon-vacancy (SiV – ) centers in diamond exhibit narrow optical transitions and favorable photophysical properties for quantum photonics and sensing. In microdiamonds, however, electrical control of color-center charge states remains challenging due to their small size, surface- and interface-dominated electronic structure, and the lack of reliable electrical contacts. Here, we report a noncontact strategy for electrically modulating microdiamond powders using nanosecond high-voltage pulses applied at kilohertz repetition rates across a hybrid architecture in which microdiamonds are deposited on electrically insulating bulk CVD diamond substrates. Sustained pulse excitation leads to pronounced and reversible suppression of zero-phonon-line emission from SiB, SiV –, and SiV 0 centers under applied voltages up to 10 kV. Voltage-, frequency-, and temperature-dependent measurements indicate that the modulation arises from charge-redistribution-induced shifts of the local Fermi level within the microdiamond layer, which transiently destabilize the emissive negative charge states. Time-resolved PL reveals recovery dynamics on second time scales consistent with trap-assisted re-equilibration of the local Fermi level mediated by surface and interface states. Measurements across multiple substrates confirm that the response is intrinsic to the microdiamonds and exhibits the opposite polarity to the voltage-enhanced SiV – emission reported in bulk diamonds. This hybrid diamond platform establishes a scalable route to charge redistribution modulation control of nanoscale color centers, providing a versatile framework for probing charge-state dynamics in surface-dominated quantum nanomaterials.
This work is focused on the investigation of the X‐ray's interaction with the color centers in diamond. X‐rays have the high penetrating power of radiation, which allows performing unhindered modifications deeply in the bulk of diamond crystals. Herein, it is shown that X‐rays irradiation of diamond can change the charge states of its defects, including silicon‐vacancy (SiV) and nitrogen‐vacancy (NV) color centers. By studying low‐temperature absorption spectra, it is shown that negatively charged SiV− and NV− centers partially transform into neutrally charged SiV0 and NV0 centers, accordingly. In addition, new absorption lines are registered, which may belong to other charge states of color centers. The results open a new way for the study of charge states for defects in various crystals (not limited to diamond), as well as allow the control over the charge state of color centers for diamond‐based quantum optics.
The charge state of a quantum point defect in a solid-state host strongly determines its optical and spin characteristics. Consequently, techniques for controlling the charge state are required to realize technologies for quantum networking and sensing. In this work, we demonstrate the use of deep-ultraviolet (DUV) radiation to dynamically neutralize nitrogen- (NV) and silicon-vacancy (SiV) centers. We first examine the neutralization of NV by correlating the NV – and NV 0 spectra, indicating > 99% polarization into NV 0 . We then examine the time dynamics of SiV – photoluminescence, observing an 80% reduction of intensity within a single 100 μs DUV pulse. Finally, we demonstrate that this DUV-induced bleaching is accompanied by a dramatic increase in the SiV 0 population that is robust to extended periods of near-infrared excitation. Our results indicate the potential of above-band gap excitation as a universal means of generating neutral charge states of quantum point defects on demand.
Group IV vacancy color centers in diamond are promising spin-photon interfaces with strong potential for applications in photonic quantum technologies. Reliable methods for controlling and stabilizing their charge state are urgently needed for scaling to multiqubit devices. Here, we manipulate the charge state of silicon vacancy (SiV) ensembles by combining luminescence and photocurrent spectroscopy. We controllably convert the charge state between the optically active SiV − and dark SiV 2− with megahertz rates and >90% contrast by judiciously choosing the local potential applied to in-plane surface electrodes and the laser excitation wavelength. We observe intense SiV − photoluminescence under hole capture, measure the intrinsic conversion time from the dark SiV 2− to the bright SiV − to be 36.4(67) ms, and demonstrate how it can be enhanced by a factor of 10 5 via optical pumping. Moreover, we obtain previously unknown information on the defects that contribute to photoconductivity, indicating the presence of substitutional nitrogen and divacancies.