Calculations and Electron Paramagnetic Resonance Measurements*

SiC is widely used in high-power, high-frequency electronic devices. It has also been used as a building block in hybrid nanocomposites for photovoltaics. Analogous to Si, SiC features SiO₂ as native oxide that can be used for passivation and insulating layers. However, a significant number of defect states are reported to form at SiC/SiO₂ interfaces, limiting mobility and increasing recombination of free charge carriers. Combining ab initio g-tensor and hyperfine interactions calculations with electron paramagnetic resonance (EPR) measurements, we show that carbon antisite dangling bond (Csi-db) defects explain the measured EPR signatures. Csi-db is found to be strongly stabilized at the interface, because carbon changes its hybridization from sp³ in the SiC-bulk to sp² at the interface, creating a dangling bond inside a porous region of the SiO₂ passivating layer. The calculated energy level of a neutral Csi-db coincides with the barrier height of the interface states from internal photoemission (IPE) of SiC/SiO2 interfaces, indicating a contribution of Csi-db to the measured interface states.