Metal-oxide-semiconductor (MOS) capacitors and MOS field-effect transistors (MOSFETs) fabricated on the carbon face of 4H-SiC were characterized following different postoxidation annealing methods used to passivate the oxide-semiconductor (O-S) interface. Of the various processes studied, sequential postoxidation annealing in NO followed by atomic hydrogen gave the lowest interface trap density ( D it). Direct oxidation/passivation in NO yielded somewhat better I- V characteristics, though all passivation ambients produced approximately the same breakdown field strength. n-Channel MOSFETs showed high channel mobility at low field, which is likely caused by the presence of mobile ions at the O-S interface. Comparisons with the silicon face are presented for interface trap density, oxide breakdown field, and channel mobility. These comparisons suggest that the carbon face does not offer significant performance advantages.