A New Structural Model for Si/SiO sub 2 Interfaces Derived from Spherosiloxane Clusters: Implications for Si 2p Photoemission Spectroscopy

Si 2p photoemission is perhaps the most widely used technique for studying the structure of the Si/SiO sub 2 interface. Traditionally, these spectra have been interpreted based on the formal oxidation state model, where the binding energy of the Si 2p core level increases nearly linearly with the number of neighboring oxygen atoms. However, this model was challenged in 1993 by Banaszak Holl and McFeely, who prepared new Si/SiO sub 2 interfaces by a chemical reaction of known molecular spherosiloxane clusters (formula H sub 8 Si sub 8 O sub (12) on Si(100). Based on the photoemission measurements of the resulting "known" interface, they suggested that the conventional oxidation state model is completely incorrect and that second nearest neighbor effects in Si 2p photoemission are very large. In this letter, we investigate the Si/SiO sub 2 interface structure formed by the chemisorption of H sub 8 Si sub 8 O sub (12) and other spherosiloxane clusters on Si(100) and resolve this long-standing controversy.