  We have developed a classical two- and three-body interaction potential to
simulate the hydroxylated, natively oxidised 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 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 oxidised 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
oxidised and amorphous silica surfaces of 97 mJ/m2 and 90mJ/m2, respectively,
at a water adsorption coverage of approximately 1 monolayer. The difference
arises from the stronger interaction of the natively oxidised surface with
liquid water, resulting in a higher heat of immersion (203 mJ/m2 vs. 166
mJ/m2), and may be explained in terms of the more pronounced water structuring
close to the surface in alternating layers of larger and smaller density 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.
