Spin multiplicity and charge state of a silicon vacancy (TV2a) in 4H-SiC determined by pulsed ENDOR

In this paper, we unambiguously re-determine the spin multiplicity of TV2a by pulsed electron nucleus double resonance technique. The TV2a center is one of the most commonly observed defects in 4H-SiC, and its origin was identified as one belonging to a class of negatively charged silicon vacancy by means of continuous-wave electron paramagnetic resonance (EPR) and the two-dimensional nutation method of pulsed EPR technique. However, a model with the spin multiplicity of triplet (S=1) and the neutral charge state has recently been suggested. Our result clearly shows that TV2a is a quartet spin (S=3∕2) state and thus should be single-negatively charged (−1)