The role of surface stress in reconstruction, epitaxial growth and stabilization of mesoscopic structures

The role of stress at solid surfaces in a vacuum environment and in contact with a liquid electrolyte in reconstruction, epitaxial growth and self-organization or stabilization of mesoscopic structures is critically reviewed. Starting from the definitions of the surface stress, the status of our current understanding of the physical origin of the surface stress on clean surfaces and of the changes of the stress upon deposition of adsorbates or foreign material is discussed. Changes in the surface stress can be measured using the cantilever bending method. The relevant equations for the elastic bending are derived. It is shown that the data analysis in previous work needs revision. Several examples are presented where the surface stress is either the driving force for the reconstruction of the surface or is at least facilitating the reconstruction. The traditional concept of the critical thickness of a heteroepitaxially grown pseudomorphic film is based on the consideration of the elastic strain energy caused by the misfit of the film and substrate lattices. It is shown that the interface stress contributes significantly to the elastic energy and hence to the stability or instability of pseudomorphic thin films. Inhomogeneous surface stresses can give rise to a self-organization of mesoscopic structures on surfaces. The theoretical background for this phenomenon is reviewed and examples are discussed.