Probing surface-adlayer conjugation on organic-modified Si(111) surfaces with microscopy, scattering, spectroscopy, and density functional theory

Joshua A. Kellar, Jui Ching Lin, Jun Hyun Kim, Nathan L. Yoder, Kirk H. Bevan, Grace Y. Stokes, Franz M. Geiger, Son Binh T. Nguyen, Michael J. Bedzyk, Mark C. Hersam

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

Highly conjugated molecules bound to silicon are promising candidates for organosilicon electronic devices and sensors. In this study, 1-bromo-4-ethynylbenzene was synthesized and reacted with a hydrogen-passivated Si(111) surface via ultraviolet irradiation. Through an array of characterization and modeling tools, the binding configuration and morphology of the reacted molecule were thoroughly analyzed. Atomic force microscopy confirmed an atomically flat surface morphology following reaction, while X-ray photoelectron spectroscopy verified reaction to the surface via the terminal alkyne moiety. In addition, synchrotron X-ray characterization, including X-ray reflectivity, X-ray fluorescence, and X-ray standing wave measurements, enabled sub-angstrom determination of the position of the bromine atom with respect to the silicon lattice. This structural characterization was quantitatively compared with density functional theory (DFT) calculations, thus enabling the p-conjugation of the terminal carbon atoms to be deduced. The X-ray and DFT results were additionally corroborated with the vibrational spectrum of the organic adlayer, which was measured with sum frequency generation. Overall, these results illustrate that the terminal carbon atoms in 1-bromo-4- ethynylbenzene adlayers on Si(111) retain φ-conjugation, thus revealing alkyne molecules as promising candidates for organosilicon electronics and sensing.

Original languageEnglish
Pages (from-to)2919-2927
Number of pages9
JournalJournal of Physical Chemistry C
Volume113
Issue number7
DOIs
Publication statusPublished - Feb 19 2009

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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