Border traps in 6H-SiC metal-oxide-semiconductor capacitors investigated by the thermally-stimulated current technique

We demonstrate the usefulness of the thermally-stimulated current (TSC) tec hnique for investigating shallow interface state defects in silicon carbide metal-oxide-semiconductor (MOS) structures. For dry oxides, low-temperatur e TSC measurements reveal a high density of near-interfacial oxide traps (b order traps) close to the band edges of 6H-SiC. Furthermore we find that an nealing the SiC/SiO2 interface in pyrogenic steam at 950 degreesC (reoxidat ion) essentially reduces the density of deep interface states, while it inc reases the density of shallow states. Our results agree with observations o f the appearance of a negative oxide charge in reoxidized MOS capacitors an d the corresponding increase of the threshold voltage in n channel metal-ox ide-semiconductor field-effect transistors. (C) 2001 American Institute of Physics.