Fabrice Didier

The van der Waals contribution to the adhesion energy at metal-oxide interfaces

Abstract The van der Waals contribution to the adhesion energy between a metal and an insulating oxide is expressed in terms of a dielectric continuum model. Values derived from the model are shown to give a good qualitative account for experimental data. Furthermore, they are seen to reproduce commonly reported trends in adhesion energy at metal-oxide interfaces since they tend to increase as the plasmon energy of the metal increases and/or as the bandgap of the insulator narrows. Such a model does not account for kinetic energy and electrostatic contributions; its relevancy to describe the adhesion energy in the metal-oxide case is discussed, and shown to be plausible provided the oxide energy gap is wide enough and the metal is sufficiently nonreactive.

Layer-by-layer growth mode of silver on magnesium oxide (100)

Abstract The growth mode of silver thin films on MgO(100) is shown to strongly depend on the chemical purity of the oxide surface. On a carbon- and defect-free surface the silver deposit grows layer-by-layer, while the presence of any of these chemical defects prevents such a growth mode.

Simple Views on Metal/Oxide Interfaces: Contributions of the Long-Range Interactions to the Adhesion Energy

Abstract The image and van der Waals contributions to the metal/oxide work of adhesion are compared through the extent to which they follow the known prevalent trends, i.e. the increase in work of adhesion (a) with narrowing oxide band gap and (b) with increasing conduction electron density of the metal. The van der Waals interaction is shown to follow both trends, while the image term is suggested to be significant only for dense metals in contact with very ionic oxides. The relative contribution of these long-range interactions to the overall metal/oxide work of adhesion is found to be maximized for systems involving metals with low electronic densities and oxides with wide band gaps. At variance, high metallic electronic densities and narrow oxide gaps likely favour short-range interactions arising from charge transfer.

Contribution of the van der Waals forces to the work of adhesion at metal / oxide interfaces

The van der Waals contribution to the work of adhesion at metal/oxide interfaces is analytically derived within the framework of a dielectric continuum model. Calculated estimates are shown to reproduce nicely the trends deduced from measurements of the overall adhesion energy, indicating that van der Waals forces play a significant role in the adhesion mechanism. The relative contribution of the van der Waals interaction in the work of adhesion is discussed and is shown to be possibly important when low-density metals and large band-gap oxides are concerned.