Nonradiative carrier capture in nitrogen and nitrogen-vacancy center in diamond

The nitrogen-vacancy (NV) center in diamond is the prototype quantum defect and enables a variety of diamond-based quantum technologies. The performance of the NV center, however, can be influenced by substitutional nitrogen (N) impurities, which are a source of spin noise and may act as charge traps. To understand this process, we conduct comprehensive first-principles density functional theory calculations to assess the nonradiative processes enabled by multiphonon emission (MPE) in both the NV center and N impurities in diamond. We find a high electron and hole capture coefficient (~10^-5 cm³ s^-1) for the (+/0) transition for N impurities, highlighting their potential role in charge dynamics. We also report transitions for the NV center, including those involving excited states. We identified the ²A₂-to-³A₂ and ³E-to-²E transitions as having high capture coefficients. These processes play a crucial role in charge state dynamics which can impact the spin-to-charge conversion mechanism. Our work clarifies the mechanisms that lead to charge instabilities and spin noise in the NV center.