EPR STUDIES OF SIC/SIO2 INTERFACES IN N-TYPE 4H- AND 6H- OXIDIZED POROUS SIC

We have investigated the interface and oxide defects in SiC/SiO2 by electron paramagnetic resonance spectroscopy (EPR) using oxidised porous SiC of 4H and 6H polytypes. Two paramagnetic defects generated by 1000°C furnace oxidation in dry oxygen could be detected in both polytypes. Their EPR parameters are very similar: the first is a spin S=1/2 center with an isotropic g-factor of 2.0028; it is attributed to a carbon related defect within the thin oxide layer. The second defect is equally a spin S=1/2 center of trigonal symmetry with principal g values of g//=2.0023 and g⊥=2.0031. The study of its hyperfine interactions and the analogy between this defect and the well known Pb0 centre in Si/SiO2 lead us to attribute this defect to a carbon dangling bond center •C-Si3 at the SiC interface plane. The interface defects are electrically active and compensate the nitrogen dopant. From photo EPR the level position is evaluated to Ec-1.8eV in the 4H polytype