The formation and solubility of silicon oxycarbides at the SiO2/SiC interface was investigated using nuclear reaction analyses. The amount of silicon oxycarbides formed by thermal oxidation of SiC in dry O-2 was seen to be independent of substrate polytype, surface termination, and oxidation temperature. Oxide growth was retarded on surfaces containing residual silicon oxycarbides, and none of several acid and oxidizing wet etch chemistries was able to remove them. (C) 2008 The Electrochemical Society.