Interface properties of metal-oxide-semiconductor structures on n-type 6H and 4H-SiC

This work reports on the interface properties of metal-oxide-semiconductor (MOS) structures formed by thermal oxidation of n-type silicon carbide (SiC). The SiC layers, grown homoepitaxially on the silicon-face of 6H-SiC and 4H-SiC substrates, were oxidized at 1100 degrees C in dry or wet atmosphere. The interface properties of the MOS structures were investigated using both, the Terman and the high-low frequency method. The validity of these methods for wide band-gap semiconductors is clarified in a short theoretical analysis. The experimental results reveal moderate densities of interface states for MOS devices on 6H-SiC as well as on 4H-SiC. Only minor differences were observed between both polytypes. Current-voltage measurements prove earlier results and show good quality independent of the polytype used as substrate material. (C) 1996 American Institute of Physics.