Fermi Level-Mediated Charge-State Control of Multicolor Diamond Microcrystals Using High-Voltage Pulses

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 SiV0 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.