PECVD and Thermal Gate Oxides on 3C vs. 4H SiC - Impact on Leakage, Traps and Energy Offsets

Energy-band model offsets, trap density distributions and gate leakage characteristics of MOS capacitors with PECVD and thermal gate oxides on 3C- and 4H-SiC were compared. The difference in trap energy distributions between the polytypes demonstrated in this experiment confirms that the 3C-SiC polytype is less vulnerable to near-interface traps (NIT) which are found in high density in the 4H-SiC. It was also shown that the nitridation of SiO2 on SiC improves the leakage properties of the gate oxides. Finally, the energy band model of the SiC MOS devices was described quantitatively which could be considered in further development of the devices and processes.