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 language | English |
|---|---|
| Pages (from-to) | 20426-20434 |
| Number of pages | 9 |
| Journal | Journal of Physical Chemistry B |
| Volume | 110 |
| Issue number | 41 |
| DOIs | |
| Publication status | Published - Oct 19 2006 |
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- Physical and Theoretical Chemistry
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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 journal › Article
}
TY - JOUR
T1 - Infrared spectroscopic investigation of the reaction of hydrogen-terminated, (111)-oriented, silicon surfaces with liquid methanol
AU - Michalak, David J.
AU - Rivillon, Sandrine
AU - Chabal, Yves J.
AU - Estève, A.
AU - Lewis, Nathan S
PY - 2006/10/19
Y1 - 2006/10/19
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=33751260194&partnerID=8YFLogxK
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U2 - 10.1021/jp0624303
DO - 10.1021/jp0624303
M3 - Article
VL - 110
SP - 20426
EP - 20434
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
SN - 1520-6106
IS - 41
ER -