Spectroscopic Observation of the Interface States at the SiO₂/4H-SiC(0001) Interface

We obtained the energy distribution of the interface states at the SiO2/4H-SiC(0001) interface using operando hard x-ray photoelectron spectroscopy. Two types of interface states were observed: one with continuous interface states in the entire SiC band-gap and the other with sharp interface states formed below the conduction band minimum (CBM). The continuous interface states in the whole gap were attributed to carbon clusters while the sharp interface states observed near the CBM were due to the Si2—C=O state and/or the Si2—C=C—Si2 state at the SiO2/SiC interface