X-Ray Scattering Study of Epitaxial Oxides on Si(001)

The structure of the Si(001)-SiO sub 2 interface has been studied using grazing incidence x-ray scattering techniques. The measured x-ray diffraction patterns correspond to a two-fold symmetric epitaxial interfacial structure. Among the many models tested, such as a buried dimer reconstruction and an oxide with the cristobalite structure, only the model of an epitaxial, ~ 5angstroms thick tridymite layer was in agreement with our data. The degree of ordering of this oxide, both parallel and perpendicular to the surface, is found to be critically dependent on the flatness of the initial silicon surface.