The acceptor level for vanadium in 4H and 6H SiC

Electron paramagnetic resonance (EPR) and temperature-dependent Hall measurements were performed on seven different vanadium-doped semi-insulating SiC samples. Comparison of the EPR data and carrier activation energy suggests that the acceptor level for vanadium is 1.1 eV below the conduction band edge (Ec) in 4H SiC and within 0.86 of Ec in the 6H polytype. Photo-induced EPR results support the level assignments. However, analysis of the V4+ spectra in 4H samples suggests that the dominant vanadium EPR signal monitored in the 4H samples used for this experiment does not represent a simple isolated impurity. Rather, the results reflect a strained or complex defect.