A strong reduction in the density of near-interface traps at the SiO2∕4H-SiC interface by sodium enhanced oxidation

This paper demonstrates how sodium enhanced oxidation of Si face 4H-SiC results in removal of near-interface traps at the SiO2∕4H-SiC interface. These detrimental traps have energy levels close to the SiC conduction band edge and are responsible for low electron inversion channel mobilities (1–10cm2∕Vs) in Si face 4H-SiC metal-oxide-semiconductor field effect transistors. The presence of sodium during oxidation increases the oxidation rate and suppresses formation of these near-interface traps resulting in high inversion channel mobility of 150cm2∕Vs in such transistors. Sodium is incorporated by using carrier boats made of sintered alumina during oxidation or by deliberate sodium contamination of the oxide during the formation of the SiC∕SiO2 interface.