Electrical characterization of instabilities in 6H silicon carbide metal-oxide-semiconductor capacitors

Capacitance, charge, and current measurements have been performed on p-type 6H-SiC metal-oxide-semiconductor capacitors in order to study electrical instabilities in the SiO2/6H-SiC system and the behavior of the inversion layer at different temperatures. The analysis of hysteresis and deformation of capacitance-voltage curves shows the presence of interface states and oxide traps with a density of approximately 5–7×1010 eV−1 cm−2 in the midgap and a peak of 3×1012 eV−1 cm−2 at E=Ev+0.53 eV. Ionic contamination of the oxide layer has also been investigated, by thermally stimulated ionic current: A mobile charge concentration in the range of 1012 cm−2 was found. Finally, it is shown, by charge-voltage measurements, that the minority-carrier generation is assisted by deep levels during the formation of the inversion layer.