Insights into the formation mechanisms of Si-OR monolayers from the thermal reactions of alcohols and aldehydes with Si(111)-H

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DOIResolve DOI: http://doi.org/10.1021/la991678z
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TypeArticle
Journal titleLangmuir
ISSN0743-7463
Volume16
Issue19
Pages74297434; # of pages: 6
AbstractHydrogen-terminated Si(111) reacts thermally at moderate temperatures with alcohols (RCH₂OH) and aldehydes (RCHO) to form the corresponding Si-OCH₂R films. The films are characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). While FTIR and XP spectroscopies suggest that films of similar composition are formed, AFM and the relative chemical stabilities of the organic films show that the two reactions do not result in structurally identical films. A mechanism for the reaction of the aldehyde with Si(111)-H is proposed which is analogous to the well-known hydrosilylation of aldehydes. The reaction proceeds either by nucleophilic addition/hydride transfer or by a radical chain mechanism via adventitious radical initiation. The alcohol reaction is similar to the chemical etching of Si(111)-H by water and short-chain alcohols. This reaction proceeds by nucleophilic attack followed by loss of dihydrogen. Traces of ammonium fluoride or water on the surface result in etching of the terraces on a time scale which is much faster than the reaction of the alcohol but not of the aldehyde. This etching can be completely suppressed by the addition of chlorotrimethylsilane to the reaction mixture. This reagent quickly scavenges both water and fluoride from the surface and reaction mixture. It is suggested that this may be a useful reagent to scavenge undesirable nucleophiles during wet chemical modification of Si(111)-H.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada; NRC Steacie Institute for Molecular Sciences
Peer reviewedNo
Identifier10367391
NRC number43846
NPARC number12330178
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Record identifier93ab849c-da50-41ab-9716-5760940c06a9
Record created2009-09-10
Record modified2016-05-09
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