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

Abstract

4H-silicon carbide (SiC) metal–oxide–semiconductor field-effect transistors fabricated on both (112̄0) and (0001) faces were characterized at various temperatures. From the temperature dependence of channel mobility, carrier transport in the inversion layer at the SiO2/4H-SiC(112̄0) interface was found to be affected by phonon scattering (μ0∼T−2.2), while that at the SiO2/4H-SiC(0001) interface was thermally activated (μ0∼T2.6) 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 SiO2/4H-SiC(112̄0) interface, but quite high (>1013 cm−2 eV−1) at the SiO2/4H-SiC(0001) interface. The low density of acceptor-like interface states near the conduction band edge on the (112̄0) face should be the primary cause for the high inversion-channel mobility.