  When annealing a 4H silicon carbide (SiC) crystal, a sequence of optically
active defect centers occurs among which the TS center is a prominent example.
Here, we present low-temperature photoluminescence analyses on the single
defect level. They reveal that the three occurring spectral signatures TS1, TS2
and TS3 originate from one single defect. Their polarization dependences expose
three different crystallographic orientations in the basal plane, which relate
to the projections of the nearest neighbor directions. Accordingly, we find a
three-fold level-splitting in ensemble studies, when applying mechanical
strain. This dependency is quantitatively calibrated. A complementary
electrical measurement, deep level transient spectroscopy, reveals a charge
transition level of the TS defect at 0.6 eV above the valence band. For a
future identification, this accurate characterization of its optical and
electronic properties along with their response to mechanical strain is a
milestone.
