Characterization of electrically active deep level defects in 4H and 6H SiC

Electrically active deep level defects have been characterized in n-type 6H- and 4H-SiC utilizing deep level transient spectroscopy (DLTS). In both polytypes, defects are observed in the as-grown state. In 6H-SiC two levels in the energy gap at 0.34 and 0.41 eV below the conduction band edge (E c) are suggested as being intrinsic in nature as their concentration increases after 2 MeV electron irradiation. Additionally, a level 0.51 eV below E c observed after electron or deuterium irradiation anneals out completely below 300°C. In as-grown epitaxial layers of the 4H-SiC polytype, a level 0.70 eV below E c is found with a capture cross-section of 4 × 10 −14 cm 2 and a concentration at or below 1 × 10 13 cm −3 exhibits acceptor-like behavior. Secondary ion mass spectrometry (SIMS) profiling reveals no evidence for Ti, V, or Cr incorporation into the epitaxial layers above ≈10 13 cm −3.