Voltage-controlled switching of the charge state of Si-vacancy defects and N-vacancy defects in diamond

We report a voltage-controlled mechanism by which the photoluminescent (PL) emission from silicon-vacancy (SiV) defects and nitrogen-vacancy (NV) defects in diamond can be modulated. These voltage-induced changes in charge states are probed by their photoluminescence spectral analysis. In particular, we can selectively produce emission from the negatively charged state of the silicon-vacancy defect (i.e., SiV^-), which exhibits narrow (Γ = 4 nm) emission at 738 nm. 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. The high-voltage pulses also enable manipulating the charge states of NV defects efficiently. Based on electrostatic simulations, we estimated the local electric field intensity near the tip of the Cu electrode to be 2.8 x 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.

 

Weng, et al., Applied Physics Letters, 119, 171101 (2021). https://doi.org/10.1063/5.0066537

 

Pambukhchyan, et al., Materials for Quantum Technology. Volume 3, page 035005 (2023). https://iopscience.iop.org/article/10.1088/2633-4356/acf750