Colour centres with long-lived spins are established platforms for quantum
sensing and quantum information applications. Colour centres exist in different
charge states, each of them with distinct optical and spin properties.
Application to quantum technology requires the capability to access and
stabilize charge states for each specific task. Here, we investigate charge
state manipulation of individual silicon vacancies in silicon carbide, a system
which has recently shown a unique combination of long spin coherence time and
ultrastable spin-selective optical transitions. In particular, we demonstrate
charge state switching through the bias applied to the colour centre in an
integrated silicon carbide opto-electronic device. We show that the electronic
environment defined by the doping profile and the distribution of other defects
in the device plays a key role for charge state control. Our experimental
results and numerical modeling evidence that control of these complex
interactions can, under certain conditions, enhance the photon emission rate.
These findings open the way for deterministic control over the charge state of
spin-active colour centres for quantum technology and provide novel techniques
for monitoring doping profiles and voltage sensing in microscopic devices