High field-effect mobility in n-channel Si face 4H-SiC MOSFETs with gate oxide grown on aluminum ion-implanted material

We report investigations of Si face 4H-SiC MOSFETs with aluminum (Al) ion-implanted gate channels. High-quality SiO₂-SiC interfaces are obtained both when the gate oxide is grown on p-type epitaxial material and when grown on ion-implanted regions. A peak field-effect mobility of 170 cm²/V·s is extracted from transistors with epitaxially grown channel region of doping 5×10¹⁵ cm^-3. Transistors with implanted gate channels with an Al concentration of 1×10¹⁷ cm^-3 exhibit peak field-effect mobility of 100 cm²/V·s, while the mobility is 51 cm²/V·s for an Al concentration of 5×10¹⁷ cm^-3. The mobility reduction with increasing acceptor density follows the same functional relationship as in n-channel Si MOSFETs.