In solid-state materials, the term superlattice usually means a synthetically prepared set of lattice planes, of variable thickness and composition, lying parallel to those of the host (substrate). (Such a structure is also known as an artificially layered structure or artificial crystal.) Similarly, in the case of extended molecular adlayers (adsorbed layers), interactions between the terminal atoms of the adsorbed molecule and the solid surface, acting in concert with strong intramolecular interactions, can lead to formation of a self-assembled monolayer. The monolayer structure is, in a sense, a superlattice with only one artificial lattice plane extending from the substrate, with a composition and thickness that can be controlled by choice of adsorbate.