Water Exclusion at the Nanometer Scale Provides Long-Term Passivation of Silicon (111) Grafted with Alkyl Monolayers

This work is a quantitative study of the conditions required for a long-term passivation of the interface silicon−alkyl monolayers prepared by thermal hydrosilyation of neat 1-alkenes on well-defined H−Si(111) surfaces. We present electrochemical capacitance measurements (C − U) in combination with...

Full description

Saved in:
Bibliographic Details
Published in:The journal of physical chemistry. B 2006-03, Vol.110 (11), p.5576-5585
Main Authors: Gorostiza, P, Henry de Villeneuve, C, Sun, Q. Y, Sanz, F, Wallart, X, Boukherroub, R, Allongue, P
Format: Article
Language:English
Subjects:
Alkenes - chemistry
Carbon - chemistry
Electrochemistry
Hydrogen - chemistry
Membranes, Artificial
Microscopy, Atomic Force
Nanotechnology
Organosilicon Compounds - chemistry
Silicon - chemistry
Spectrum Analysis
Surface Properties
Water - chemistry
X-Rays
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:This work is a quantitative study of the conditions required for a long-term passivation of the interface silicon−alkyl monolayers prepared by thermal hydrosilyation of neat 1-alkenes on well-defined H−Si(111) surfaces. We present electrochemical capacitance measurements (C − U) in combination with ex situ atomic force microscopy (AFM) observations and X-ray photoelectron spectroscopy (XPS) measurements. Capacitance measurements as a function of the reaction time and XPS data reveal close correlations between the chemical composition at the interface and its electronic properties. A very low density of states is found if suboxide formation is carefully prevented. The monitoring of C − U plots and AFM imaging upon exposure of the sample in diverse conditions indicate that the initial electronic properties and structure of the interface are long-lasting only when the monolayer surface coverage is θ > 0.42. A model demonstrates that this threshold value corresponds to a monolayer with intermolecular channels narrower than ∼2.82 Å, which is equal to the diameter of a water molecule. Water exclusion from the monolayer promotes long-term passivation of the silicon surface against oxidation in air and water as well as perfect corrosion inhibition in 20% NH4F. We provide two criteria to assess when a sample is optimized:  The first one is an effective dielectric constant
ISSN:1520-6106
1520-5207
DOI:10.1021/jp054825c