Energetics of surface atomic processes

Abstract

The energetics of surface atomic processes such as the binding energy of surface atoms with the substrate, the energy barrier for a surface atom to overcome to displace to a neighbor site and the interaction between two adsorbed atoms or between an adsorbed atom and a lattice step or an impurity atom in the surface layer, etc, can be studied by field ion microscope and time-of-flight atom-probe experiments. We will briefly describe methods of measuring these energies and how some of them are related. In general, the binding energy of an atom with the substrate is of the order of the cohesive energy of the solid, or a few eV. The height of the diffusion barrier for single adsorbed atoms is of the order of several tenths of an eV, or about one tenth the binding energy of the adatom with the substrate. The interaction energy between two adsorbed atoms or between an adatom and a substitutional impurity atom is of the order of a few tens of meV, and is thus another order of magnitude smaller than the diffusion barrier height.