Spin multiplicity and charge state of a silicon vacancy(TV2a)in4H-SiC determined by pulsed ENDOR

In this paper, we unambiguously re-determine the spin multiplicity of $T_{V2a}$ by pulsed electron nucleus double resonance technique. The $T_{V2a}$ 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 $T_{V2a}$ is a quartet spin $(S=3∕2)$ state and thus should be single-negatively charged $(-1)$.