Atom-scale optical determination of Si-oxide layer thickness during layer-by-layer oxidation: Theoretical study

Optical anisotropy spectra of SiO2/Si(001) interfaces were theoretically investigated based on the sp3s* tight-binding calculation. In the spectra, we found three types of optical transitions originating from the E1 and E2 transitions of bulk Si, the interface Si–Si bonds, and the dangling-bond states at the interface. It was shown that the sign of these transitions oscillates during the layer-by-layer oxidation, which indicates that by counting the oscillation one can determine the layer thickness of oxidized Si layers in an atomic scale.