Oxides on SiC

Silicon carbide (SiC) is the only compound semiconductor whose native oxide is SiO/sub 2/. This makes it possible to construct a variety of MOS devices in SiC. However, the SiC MOS interface is more complex than on silicon, due to the presence of carbon in the compound and the non-cubic crystal structure. Over the last few years, the midgap interface state density on p-type 6H-SiC has been reduced from the mid-10/sup 11/ to the mid-10/sup 10/ eV/sup -1/ cm /sup -2/ range, and the fixed oxide charge from about 2/spl times/10/sup 12/ to 5/spl times/10/sup 11/ cm/sup -2/. Studies of oxide reliability are underway, and preliminary results on n-type 6H-SiC extrapolate to a lifetime of 20,000 years at a field of 3 MV/cm at 145/spl deg/C.