AVS 46th International Symposium
    Electronic Materials and Processing Division Tuesday Sessions
       Session EM-TuM

Paper EM-TuM6
How Important are Second Nearest Neighbor Effects in Silicon 2p Photoemission Spectroscopy of Si/SiO@sub 2@ Interfaces?

Tuesday, October 26, 1999, 10:00 am, Room 608

Session: Si Surface Chemistry and Etching, Passivation, and Oxidation
Presenter: J. Eng, Jr., Bell Labs, Lucent Technologies
Authors: J. Eng, Jr., Bell Labs, Lucent Technologies
K. Raghavachari, Bell Labs, Lucent Technologies
Correspondent: Click to Email
The proper interpretation of Si 2p photoemission spectra of Si/SiO@sub 2@ interfaces has been a controversial topic since 1993, when Banaszak-Holl and McFeely proposed that second nearest neighbor effects can cause significant chemical shifts in Si 2p photoemission features.@footnote 1@ Their claims were based upon model Si/SiO@sub 2@ surfaces produced by the adsorption of H@sub 8@Si@sub 8@O@sub 12@ clusters on Si(100) at room temperature. Arguing that the clusters are bonded to Si(100) dimers through a single vertex (due to Si-H bond cleavage), they proceeded to correlate the relative peak positions and peak intensities with different Si species at the interface. This correlation led them to conclude that the entire formal oxidation state framework is inadequate for interpreting Si 2p photoemission spectra of Si/SiO@sub 2@ interfaces, and that second nearest neighbor effects are important. The key issue in this controversy is understanding how the H@sub 8@Si@sub 8@O@sub 12@ clusters bond to the Si(100) surface. Using transition state calculations, we present detailed mechanistic arguments which show that the clusters do not react with the Si(100) surface through Si-H bond cleavage, but rather through Si-O bond cleavage. The resulting "cracked" cluster allows us to predict the Si 2p photoemission features of the clusters on Si(100) using the conventional formal oxidation state model, without invoking second nearest neighbor effects. Finally, the normal mode frequencies of the "cracked" cluster are in excellent agreement with infrared studies of the clusters on Si(100). @FootnoteText@ @footnote 1@ M. M. Banaszak-Holl and F. R. McFeely, Phys. Rev. Lett., 71(15) (1993) p.2441.