Sodium Enhanced Oxidation of Si-Face 4H-SiC: A Method to Remove Near Interface Traps

We demonstrate 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 (1-10 cm2/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 nearinterface traps resulting in high inversion channel mobility of 150 cm2/Vs in such transistors. Sodium can be incorporated by using carrier boats made of sintered alumina during oxidation or by deliberate sodium contamination of the oxide during formation of the SiC/SiO2 interface.