Electron paramagnetic resonance of sulfur at a split-vacancy site in diamond

In natural diamonds a sulfur-related paramagnetic center labeled W31 has been previously tentatively assigned to an interstitial sulfur species in a positive charge state. However, we show by combining an assessment of available experimental data and density functional simulations, that the hyperfine tensors can attributed to a defect made up from sulfur at the center of a di-vacancy, the so-called split-vacancy, in the negative charge state. These acceptors are highly likely to be formed in S-implanted material, and are a likely cause for high resistivity in material implanted with sulfur in the attempt to produce n-type conduction.