Distinguishing nitrogen-containing sites in SiO₂/4H-SiC(0001) after nitric oxide annealing by X-ray absorption spectroscopy

The atomic structure of nitrogen at the SiO2/4H-SiC(0001) interface has been investigated using X-ray absorption spectroscopy (XAS) in two nitric oxide annealed samples, one of which was oxidized in dry O2 (NO-POA) prior to the experiment. The peak shapes and energies of the observed and simulated spectra are in agreement and indicate that the N-containing sites could be the substitutional C site at the interface for the NO-annealed sample and the interstitial site in the interior of SiC for the NO–POA-annealed sample. XAS analysis distinguished between the N-containing sites at the SiO2/SiC interface.