Thermal chemistry of CH 3 on Si/Cu(100)

J. Han, S. I. Gheyas, Y. Wang, D. R. Strongin, A. P. Graham, B. J. Hinch, A. P. Wright

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Abstract

Photoelectron spectroscopy (PES), thermal programmed desorption (TPD) studies, and scanning tunneling microscopy (STM) investigated the interaction and chemistry of CH 3 (generated by the thermal cracking of azomethane) on Si/Cu(100). Si was deposited on Cu(100) by the thermal, decomposition of SiH 4 at 420 K. STM of adsorbate-free Si/Cu(100) at a less than saturation coverage of Si revealed a surface that contained large domains of a Cu 2Si structure. These Cu 2Si domains coexisted with regions that were believed to be lower in fractional Si coverage. TPD results showed that (CH 3) 3SiH desorbed near 200 K from CH 3/Si/Cu-(100) prepared with a low Si concentration. With increasing Si concentration a (CH 3) 3SiH desorption state appeared near 420 K, in addition to the 200 K state. The two observed TPD states of (CH 3) 3SiH at 200 and 420 K were believed to be due to the thermal reaction of CH 3 with the low Si density and high Si density (i.e., Cu 2Si) regions, respectively. At a saturation coverage of Si, when the well ordered Cu 2Si phase covered the surface, only the 420 K peak was present during CH 3/Si/Cu(100) TPD. Results also suggested that (CH 3)-Si and possibly some (CH 3) 2Si intermediates predominated on the surface below room temperature, and (CH 3) 3-Si species were formed on the surface only at temperatures between 250 and 390 K. Surface hydrogen needed for the final evolution of (CH 3) 3SiH was generated from methyl groups at temperatures above 390 K on the Si-saturated Cu(100).

Original languageEnglish (US)
Pages (from-to)3078-3084
Number of pages7
JournalJournal of Physical Chemistry B
Volume104
Issue number14
Publication statusPublished - Apr 13 2000
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

Han, J., Gheyas, S. I., Wang, Y., Strongin, D. R., Graham, A. P., Hinch, B. J., & Wright, A. P. (2000). Thermal chemistry of CH 3 on Si/Cu(100). Journal of Physical Chemistry B, 104(14), 3078-3084.