Abstract
Monatomic sheets are generally not left alone. An atomic layer is typically on a layer of different sheets or on a surface of the substrate. Lattice parameters of two crystal layers govern the “epitaxial” growth and also dominate physical properties of the layers after their contact. The junction also induces a long-range periodic order or the Moiré pattern that characterizes electronic states, interatomic chemical bondings, and even stabilities of the system. Even layers of van der Waals crystals have been found to show the nonnegligible electronic change. This fact indicates that it is necessary to understand not only properties of the individual monatomic layers but also their variations after formation of the junctions. Moreover, this provides opportunities to artificially optimize monatomic layers by environment that will be suitable for academic or technological applications. In this chapter, issues on the interface of atomic layers, including those on surfaces, are described with examples.