Deep Levels in SiC:V by High Temperature Transport Measurements

Vanadium-doped 6H and 4H SiC have been studied with high-temperature Hall effect and resistivity, optical absorption, and SIMS. The 6H samples were found to exhibit three thermal activation energies, 0.35 eV, 0.7 eV, and near midgap. The 0.3 eV level is due to thermal ionization of residual uncompensated boron. We attribute the midgap level to thermal ionization of the vanadium donor level. The 0.7 eV activation is believed to be due to transfer of electrons from the ionized vanadium acceptor levels to the conduction band. These results suggest that the vanadium donor and acceptor levels are located at Ec - 1.42 eV and EV + 2.4 eV respectively. (Author)