SIO2/SI INTERFACE STUDY WITH SYNCHROTRON RADIATION X-RAY-DIFFRACTION

SiO2/Si(111)-7 × 7 and SiO2/Si(100)-2 × 1 interface superstructures were observed with a grazing incidence X-ray diffraction method. Interface superstructures were observed only in the samples of which SiO2 layers were deposited by a molecular beam deposition method; they were not observed in thermally oxidized samples. Intensities of fractional-order diffraction in the SiO2/Si(100)-2 × 1 system suggest that the observed superstructure is composed of dimer reconstruction like a clean surface or ordering structure of deposited silicon and oxygen atoms, but not of a crystalline SiO2, such as cristobalite or tridymite. © 1990.