We propose a method to evaluate the carrier transport properties in the inversion layer of 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) experimentally. Our approach differs from conventional methods, which have adjusted the parameters in conventional mobility models. Intrinsic phonon-limited mobility (μ phonon ) in the SiC MOSFET was observed by suppressing the severe impact of Coulomb scattering on the SiC MOS inversion layer by lowering the acceptor concentration (N A ) of the p-type well region to the order of 10 14 cm −3 . In this study, we investigated the carrier transport properties in the inversion layer of Si-face 4H-SiC MOSFETs with nitrided oxide. It is revealed that the μ phonon of the SiC MOSFET is a quarter or less than the conventionally presumed values. Additionally, surface roughness scattering is found not to be the most dominant mobility-limiting factor even at high effective normal field (E eff ) for the SiC MOSFET. These results demonstrate that conventional understanding of carrier scattering in the SiC MOS inversion layer should be modified, especially in the high E eff region.

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