Interface state density (Dit) at SiO2/4H–SiC interfaces were reported for states lying energetically within ~0.05 to 0.2eV of the conduction band edge of 4H–SiC using capacitance-voltage characterization as a function of temperature. Comparison of as-grown dry oxidized and nitrided interfaces confirms the significant reduction of Dit associated with nitridation. In the as-oxidized case (no nitridation), the Dit in the energy range ~0.05 to 0.2eV below EC was found to consist of a broad Dit peak at about 0.1eV below EC with an energy width of about ~0.2eV and a peak magnitude of about 2 x 1013/cm2eV superimposed on an exponentially decaying background distribution. Interfacial nitridation completely eliminated the broad peak but does not strongly affect the background.

Ultrashallow Defect States at SiO2/4H–SiC Interfaces. S.Dhar, X.D.Chen, P.M.Mooney, J.R.Williams, L.C.Feldman: Applied Physics Letters, 2008, 92[10], 102112