Investigation of SiO₂-SiC Interface by High-Resolution Transmission Electron Microscope

High-resolution transmission electron microscopy (HR TEM) reveals an atomically flat SiC surface after oxidation in either NO or dry O2 ambients. This reopens the question of the origin of the electronically active defects at the SiO2–SiC interface, whose density remains orders of magnitude higher than in the SiO2–Si interface. Capacitance-transient measurements, analysed in this paper, demonstrate that the dominant electronically active defects are in the oxide at tunneling distances from the SiC surface (near-interface traps). The HR TEM results cannot rule out that these traps are related to carbon/oxygen bonds or even nanometer-sized carbon clusters, which resolves the apparent inconsistency with the earlier experimental evidence of carbon accumulation at (or near) the SiO2–SiC interface.