Chemisorption Pathways and Si 2p Core Level Shifts for the Interaction of Spherosiloxane Clusters with Si(100): Implications for Photoemission in Si/SiO sub 2 Systems

Si 2p core-level photoemission spectroscopy is one of the most widely used tools for investigating the structure of the technologically important Si/SiO sub 2 interface. Three distinct peaks spaced roughly 0.9 eV apart characterize the interface region and traditionally are interpreted as resulting from silicon atoms attached to 1,2, and 3 oxygen atoms (i.e., Si sup (1+), Si sup (2+), Si sup (3+) oxidation states, respectively). 

However, this simple nearest-neighbor model was challenged in 1993 by Banaszak Holl and McFeely, who prepard 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 photoemission are very large.