Both n- and p-channel SiC MOSFETs, the gate oxides of which were annealed in NO, with various body doping concentrations were fabricated. Despite the large difference in bulk mobility between electrons (1020 cm2/Vs) and holes (95 cm2/Vs), the maximum field-effect mobility in heavily-doped (~5×1017 cm−3) MOSFETs was 10.3 cm2/Vs for the n-channel and 7.5 cm2/Vs for the p-channel devices. The measurements using body bias revealed that the field-effect mobility in both n- and p-channel SiC MOSFETs is dominated by the effective normal field rather than the body doping.

The effects of a process that minimizes oxidation of SiC on the channel mobility of heavily doped 4H-SiC (0001), (11-20), and (1-100) metal-oxide-semiconductor field-effect transistors (MOSFETs) were investigated. High field-effect mobilities were obtained for these MOSFETs even when the acceptor concentration of the p-body (N A) exceeded 1 × 1018 cm-3. The field-effect mobility for the (0001) MOSFETs reached 25 cm2/Vs (N A = 1 × 1018 cm-3). The fabricated (11-20) and (1-100) MOSFETs showed very high channel mobilities of 125 cm2/Vs (N A = 1 × 1018 cm-3) and 80 cm2/Vs (N A = 5 × 1018 cm-3), respectively.