Infrared spectroscopic investigation of the reaction of hydrogen-terminated, (111)-oriented, silicon surfaces with liquid methanol

David J. Michalak, Sandrine Rivillon, Yves J. Chabal, A. Estève, Nathan S Lewis

Research output: Contribution to journalArticle

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Abstract

Fourier transform infrared spectroscopy and first principles calculations have been used to investigate the reaction of atomically smooth, hydrogen-terminated Si(111) (H-Si) surfaces with anhydrous liquid methanol. After 10 min of reaction at room temperature, a sharp absorbance feature was apparent at ∼ 1080 cm-1 that was polarized normal to the surface plane. Previous reports have identified this mode as a Si-O-C stretch; however, the first principles calculations, presented in this work, indicate that this mode is a combination of an O-C stretch with a CH3 rock. At longer reaction times, the intensity of the Si-H stretching mode decreased, while peaks attributable to the O-C coupled stretch and the CH3 stretching modes, respectively, increased in intensity. Spectra of H-Si(111) surfaces that had reacted with CD3OD showed the appearance of Si-D signals polarized normal to the surface as well as the appearance of vibrations indicative of Si-OCD3 surface species. The data are consistent with two surface reactions occurring in parallel, involving (a) chemical attack of hydrogen-terminated Si(111) terraces by CH3OH, forming Si-OCH 3 moieties having their Si-O bond oriented normal to the Si(111) surface and (b) transfer of the acidic hydrogen of the methanol to the silicon surface, either through a direct H-to-D exchange mechanism or through a mechanism involving chemical step-flow etching of Si-H step sites.

Original languageEnglish
Pages (from-to)20426-20434
Number of pages9
JournalJournal of Physical Chemistry B
Volume110
Issue number41
DOIs
Publication statusPublished - Oct 19 2006

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Silicon
Methanol
Hydrogen
methyl alcohol
Infrared radiation
Liquids
silicon
hydrogen
liquids
Stretching
chemical attack
Chemical attack
Surface reactions
reaction time
surface reactions
Fourier transform infrared spectroscopy
Etching
infrared spectroscopy
Rocks
etching

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Infrared spectroscopic investigation of the reaction of hydrogen-terminated, (111)-oriented, silicon surfaces with liquid methanol. / Michalak, David J.; Rivillon, Sandrine; Chabal, Yves J.; Estève, A.; Lewis, Nathan S.

In: Journal of Physical Chemistry B, Vol. 110, No. 41, 19.10.2006, p. 20426-20434.

Research output: Contribution to journalArticle

Michalak, David J. ; Rivillon, Sandrine ; Chabal, Yves J. ; Estève, A. ; Lewis, Nathan S. / Infrared spectroscopic investigation of the reaction of hydrogen-terminated, (111)-oriented, silicon surfaces with liquid methanol. In: Journal of Physical Chemistry B. 2006 ; Vol. 110, No. 41. pp. 20426-20434.
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