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Insights Into The Formation Mechanisms Of Si−OR Monolayers From The Thermal Reactions Of Alcohols And Aldehydes With Si(111)−H1
Published 2000 · Chemistry
Hydrogen-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 fluor...