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Lookup NU author(s): Dr Daniel Cole
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We have developed a classical two- and three-body interaction potential to simulate the hydroxylated, natively oxidized Si surface in contact with water solutions, based on the combination and extension of the Stillinger-Weber potential and of a potential originally developed to simulate SiO 2 SiO2 polymorphs. The potential parameters are chosen to reproduce the structure, charge distribution, tensile surface stress, and interactions with single water molecules of a natively oxidized Si surface model previously obtained by means of accurate density functional theory simulations. We have applied the potential to the case of hydrophilic silicon wafer bonding at room temperature, revealing maximum room temperature work of adhesion values for natively oxidized and amorphous silicasurfaces of 97 and 90mJ/m 2 90mJ∕m2 , respectively, at a water adsorption coverage of approximately 1 ML. The difference arises from the stronger interaction of the natively oxidizedsurface with liquid water, resulting in a higher heat of immersion (203 vs 166mJ/m 2 166mJ∕m2 ), and may be explained in terms of the more pronounced water structuring close to the surface in alternating layers of larger and smaller densities with respect to the liquid bulk. The computed force-displacement bonding curves may be a useful input for cohesive zone models where both the topographic details of the surfaces and the dependence of the attractive force on the initial surface separation and wetting can be taken into account.
Author(s): Cole DJ, Payne MC, Csanyi G, Spearing SM, Colombi-Ciacchi L
Publication type: Article
Publication status: Published
Journal: Journal of Chemical Physics
Print publication date: 28/11/2007
Online publication date: 27/11/2007
ISSN (print): 0021-9606
ISSN (electronic): 1089-7690
Publisher: AIP Publishing
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