Shallow dopant and surface levels in 6H-SiC MOS structures studied by thermally stimulated current technique

In this work, the shallow majority-carrier traps in 6H-SiC MOS structures are studied using thermally stimulated current (TSC) measurements in the range 6-100 K. In this temperature range, we observe TSC signals from shallow doping levels and from traps at the SiC/SiO₂ interface. The first results of the investigation of very shallow (shallower than doping levels) interface states in differently prepared structures are presented. We find that the re-oxidation anneal, which essentially reduces the density of deep interface states, results in a significant increase (by a factor of 2) in the density of shallow states near the valence band.