Positron annihilation was used to study thermally oxidized 4H- and 6H-SiC. The SiC/SiO2 interface was found to contain a high density of open-volume defects. The positron trapping at the interface defects was correlated with the charge of the interface as determined by capacitance-voltage experiments. For oxides grown on n-SiC substrates, the positron annihilation characteristics at these defects were nearly indistinguishable from those of a Si/oxide interface, with no discernable contribution from C-related bonds or C clusters. These results indicated that those defects at the SiC/oxide interface, which were visible to positrons, were similar to those at the Si/oxide interface. The positron annihilation characteristics suggested that these defects were vacancies surrounded by O atoms.

Observation of Interface Defects in Thermally Oxidized SiC using Positron Annihilation. J.Dekker, K.Saarinen, H.Ólafsson, E.Ö.Sveinbjörnsson: Applied Physics Letters, 2003, 82[13], 2020-2