The interface trap density Dit(E) has been profiled versus energy in the bandgap for 6H-SiC MOS devices. A modified "low-frequency" capacitance-voltage technique is presented which allows trap densities to be independently profiled close to the conduction and valence band edges. Results show that Dit(E) is much higher close to both band edges than the average (midgap) value. These results show that the low transconductance typically reported for n-channel 6H-SiC MOSFETs is caused by trapping of inversion layer electrons at the SiC/SiO2 interface.