Optical and electrical studies on the TS defect in 4H-SiC

Abstract 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.