The negatively charged tin-vacancy center (SnV-) in diamond is a promising Group-IV single-photon emitter, but stabilizing its charge state is the bottleneck. Using density functional theory and equilibrium defect-concentration modeling, this work shows that the SnV- charge state forms more favorably by capturing an electron from a neighboring substitutional-nitrogen donor (N_C) -- always present even in the purest diamond -- than from the host band edge, extending Collins's donor-charging mechanism for the NV to the SnV. By computing defect concentrations in equilibrium along competing formation pathways, it identifies which nitrogen-doping conditions maximize SnV- yield, suggesting concrete experimental routes for optoelectronic and quantum-information applications.
The elucidation of the mechanism of Sn$V^-$ formation in diamond is especially important as the Sn$V^-$ color center has the potential to be a superior single-photon emitter when compared to the N$V$…