AVS 52nd International Symposium
    Surface Science Thursday Sessions
       Session SS2-ThM

Paper SS2-ThM6
Correlation of Surface Electronic Structure with Organic Reactivity on Si(114)

Thursday, November 3, 2005, 10:00 am, Room 202

Session: Functionalization of Semiconductor Surfaces
Presenter: D.E. Barlow, Naval Research Laboratory
Authors: D.E. Barlow, Naval Research Laboratory
A.R. Laracuente, Naval Research Laboratory
L.J. Whitman, Naval Research Laboratory
J.N. Russell, Naval Research Laboratory
Correspondent: Click to Email
Si(114)-(2x1) is a stable high-index surface oriented 19.5° between (001) and (111). The equilibrium surface reconstruction is comprised of parallel rows of dimers, rebonded atoms, and tetramers, with all the rows oriented along the same crystallographic direction.@footnote 1@ The different Si(114) structural motifs within each row have distinct electronic structures, making this surface an ideal template for studying the relationship between adsorption site geometry (including symmetry), local electronic structure, and chemisorption of organic molecules on clean silicon surfaces. In this study, we have experimentally characterized the effects of charge transfer, @pi@ bonding, orbital symmetry, and di-radical reaction pathways on the cycloaddition chemisorption of ethylene on Si(114)-(2x1). Transmission FTIR spectroscopy was used to confirm the basic chemical structure and orientation of the chemisorbed ethylene. The results indicate a di-@sigma@ bonded product with a C-C bond axis preferentially oriented along the row direction. Using atomic-resolution STM, we identified three common adsorption structures located at the dimer, rebonded atom, and tetramer sites. In correlation with the FTIR results, these structures can be identified as [2+2] cycloaddition products, bridged rebonded atoms, and [4+2] cycloaddition products, respectively. The order of site reactivity is found to be rebonded atoms > dimers > tetramers. Reasons for this reactivity trend will be discussed. @FootnoteText@ @footnote 1@S. C. Erwin, A. A. Baski, and L. J. Whitman, Phys. Rev. Lett. 77, 687 (1996).