Planar n-channel MOSFETs have been fabricated on 4H-SiC (11-20), (0001) and (000-1) faces by using oxidation in N2O ambient. The relationship between the MOSFET performance and the acceptor concentration (7x10(15)-2x10(17)cm(-3)) of epilayers has been investigated. 4H-SiC (11-20) MOSFETs have shown a high effective channel mobility of 70 cm(2)/Vs at a 2x10(16) cm(-3) doping, and 54 cm(2)/Vs at 2x10(17) cm(-3). Short-channel effects have been also investigated.