Determination of intrinsic phonon-limited mobility and carrier transport property extraction of 4H-SiC MOSFETs

We determined the intrinsic phonon-limited mobility in the SiC MOSFET, for the first time. Based on this finding, the carrier transport properties of 4H-SiC MOSFETs such as phonon, surface roughness and Coulomb scattering were evaluated by experimental procedures. This approach is different from the conventional methods, which have adjusted the parameters in the mobility models. It was realized due to the suppression of severe impact of Coulomb scattering on SiC MOS inversion layer by lowering the acceptor concentration of p-type well region in the order of 1014 cm−3. The phonon-limited mobility of the SiC MOSFET is revealed to be one fourth or less than conventionally presumed values. In addition, different from the conventional understanding, it was clarified that surface roughness scattering is not the most dominant mobility limiting factor even in high effective normal field for the SiC MOSFET. These results represent that conventional mobility models should be modified in high effective normal field, especially at high temperature.