Ultrashallow defect states at SiO2/4H-SiC interfaces

Interface state density (D-it) at SiO2/4H-SiC interfaces are reported for states lying energetically within similar to 0.05-0.2 eV of the conduction band edge (E-C) 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 D-it associated with nitridation. In the as-oxidized case (no nitridation), the D-it in the energy range similar to 0.05-0.2 eV below E-C is found to consist of a broad D-it peak at about similar to 0.1 eV below E-C with an energy width of about similar to 0.2 eV and a peak magnitude of similar to 2x10(13) cm(-2) eV(-1) superimposed on an exponentially decaying background distribution. Interfacial nitridation completely eliminates the broad peak but does not strongly affect the background. (c) 2008 American Institute of Physics.