A cause for highly improved channel mobility of 4H-SiC metal–oxide–semiconductor field-effect transistors on the (112̄0) face

4H-silicon carbide (SiC) metal–oxide–semiconductor field-effect transistors fabricated on both $\text{(112̄0)}$ and (0001) faces were characterized at various temperatures. From the temperature dependence of channel mobility, carrier transport in the inversion layer at the ${\mathrm{SiO}}_{\mathrm{2}}\mathrm{/4H-SiC}\text{(112̄0)}$ interface was found to be affected by phonon scattering ${\mathrm{(\mu }}_0{\mathrm{\sim T}}^{\text{−2.2}}\mathrm{),}$ while that at the ${\mathrm{SiO}}_{\mathrm{2}}\mathrm{/4H-SiC}\text{(0001)}$ interface was thermally activated ${\mathrm{(\mu }}_0{\mathrm{\sim T}}^{\text{2.6}})$ due to the decrease of Coulomb scattering by emission of electrons from acceptor-like interface states. From the temperature dependence of threshold voltage, the density of acceptor-like interface states near the conduction band edge seems to be low at the ${\mathrm{SiO}}_{\mathrm{2}}\mathrm{/4H-SiC}\text{(112̄0)}$ interface, but quite high ${\text{(>10}}^{13} {\mathrm{cm}}^{\mathrm{-2}}{\mathrm{ eV}}^{\mathrm{-1}})$ at the ${\mathrm{SiO}}_{\mathrm{2}}\mathrm{/4H-SiC}\text{(0001)}$ interface. The low density of acceptor-like interface states near the conduction band edge on the $\text{(112̄0)}$ face should be the primary cause for the high inversion-channel mobility.