Atomic Scale Surface Characterization with Photoemission of Adsorbed Xenon (PAX)

Abstract

The physical and chemical properties of solid surfaces are strongly influenced — if not dominated — by structural and chemical heterogeneities. For example, structural surface defects like steps, kinks and vacancies act as heterogeneous nucleation centers and thereby affect the growth mode and the final structure of epitaxial films and adsorbed gas layers. Chemical defects like heteroatoms are the origin of local surface structure modifications or may even trigger structural phase transitions and surface reconstruction. Both surface topography and composition are decisive parameters for the chemical reactivity and catalytic activity of solid surfaces. Surface defects and dopants (heteroatoms) create surface states in the band gap of semiconductors, which in turn determine the electronic properties of semiconductor devices. A full understanding of all kinds of surface properties and surface processes ultimately requires a characterization of real surfaces on an atomic scale. A Kossel model of a real surface is depicted in Fig. 13.1, showing schematically a binary surface with several kinds of structural defects.