  Spin defects in silicon carbide have exceptional electron spin coherence with
a near-infrared spin-photon interface in a material amenable to modern
semiconductor fabrication. Leveraging these advantages, we successfully
integrate highly coherent single neutral divacancy spins in commercially
available p-i-n structures and fabricate diodes to modulate the local
electrical environment of the defects. These devices enable deterministic
charge state control and broad Stark shift tuning exceeding 850 GHz.
Surprisingly, we show that charge depletion results in a narrowing of the
optical linewidths by over 50 fold, approaching the lifetime limit. These
results demonstrate a method for mitigating the ubiquitous problem of spectral
diffusion in solid-state emitters by engineering the electrical environment
while utilizing classical semiconductor devices to control scalable spin-based
quantum systems.
