MOS characterization of thermally oxided 6H silicon carbide

An MOS evaluation of the SIO/sub 2//SiC interface as a function of oxidation conditions and substrate doping is reported. 6H SiC (Si face) epitaxial wafers were thermally oxidized in both wet and dry ambients. MOS capacitors were formed by thermally evaporating circular aluminium field plates. Capacitance transient (C-t) measurements have been performed at elevated temperatures (260-370 degrees C). Approximate values for intrinsic carrier concentration n/sub i/ as a function of temperature in the range 270-360 degrees C have been obtained directly from the measured C-V curve. These n/sub i/ values are more than two orders of magnitude larger than would be calculated by extrapolating the accepted room temperature value. Based on these n/sub i/ values, bulk generation lifetime tau /sub G/ and surface generation velocity S/sub 0/ are calculated for an n-type sample using a modified Zerbst technique. Both tau /sub G/ and S/sub 0/ are within about a factor of 20 of the best reported silicon values.