A cause for highly improved channel mobility of 4H-SiC metal-oxide-semiconductor field-effect transistors on the (11(2)over-bar0) face

4H-silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors fabricated on both (11 (2) over bar0) 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(11 (2) over bar0) interface was found to be affected by phonon scattering (mu (0)similar toT(-2.2)), while that at the SiO2/4H-SiC(0001) interface was thermally activated (mu (0)similar toT(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 SiO2/4H-SiC(11 (2) over bar0) interface, but quite high (> 10(13) 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 (11 (2) over bar0) face should be the primary cause for the high inversion-channel mobility. (C) 2001 American Institute of Physics.