Atomic displacement free interfaces and atomic registry in SiO2∕(1×1) Si(100)

We use ion beam analysis to probe the structure and interface of ultrathin thermal oxide films grown on (1×1) Si(100) surfaces prepared using the Herbots-Atluri [U.S. patent No. 6,613,677 (Sept. 2, 2003)] wet chemical clean. We discover that these oxide layers are structurally registered with the substrate lattice with no interfacial structural disorder. Registry of Si atoms is most pronounced along ⟨111⟩ directions relative to the Si substrate, consistent with a β-cristobalite epitaxial phase. This structurally registered phase transitions to an amorphous structure approximately 2nm from the interface.