Electronic properties of solid surfaces

A significant part of the physics community is dedicated to the study of condensed matter, which essentially aims to measure, predict and explain the physico-chemical properties of solids . To achieve this, it is essential to be able to describe, understand and model the behavior of electrons in condensed matter. In any assembly of atoms (molecule, aggregate, crystalline or amorphous solid), electrons are the "glue" that holds the atomic edifice together and determines most of its physical properties, whether structural, mechanical, optical, magnetic or even vibrational. Thus, the equilibrium structure of an atomic assembly is determined by the minimum total electronic energy of all its electrons. Similarly, the optical properties of solids over a wide range of energies are dominated by electronic transitions between occupied and unoccupied electron levels. In most solids, when subjected to the action of an electric or electromagnetic field, the transport of electric current involves a displacement of electrons. Understanding the magnetic, dielectric, ferroelectric, thermal and most other physical properties of a solid therefore requires detailed knowledge of its "electronic structure", a term associated with the description of the energy levels of electrons in the solid, and more generally with a field of condensed matter physics devoted to the properties of electrons in solids.

The infinite solid model, which neglects the surface, generally describes the overall properties of the material very well, as they are the result of the individual contributions of each of the solid's atoms. In the case of a macroscopic solid, there are many more volume atoms than surface atoms. For example, a silicon cube with a side length of 1 cm comprises around 5 × 10 ²² volume atoms for just 4 × 10 ¹⁵ surface atoms. Consequently, surface properties generally only emerge by using experimental techniques that are particularly sensitive to surface atoms, or by considering processes that depend specifically on these atoms, such as crystal growth, adsorption, oxidation, corrosion, friction or heterogeneous catalysis, which cannot be described by the infinite crystal model. The transition from the civilization of steel to that of silicon, which began in the mid-twentieth century and led to the race for miniaturization, has been a major driving force behind the development of surface science. While the fraction of surface atoms in a steel beam is of the order of 10 ^–9 ...