Atomic Terrace Low Angle Shadowing (ATLAS) is a surface science technique which enables the growth of planar nanowire or nanodot arrays using molecular beam epitaxy on a vicinal surface. ATLAS utilises the inherent step-and-terrace structure of the surface as a template for such nanostructures. The technique involves the low angle incidence of flux material on vicinal substrates. Vicinal substrates are composed of atomic terraces separated by atomic steps. The ATLAS technique allows for the fabrication of well defined planar arrays of plasmonic nanostructures, of dimensions unachievable by lithography. A collimated beam of atoms or molecules is evaporated at an oblique angle to the substrate. This causes the steps to "shadow" the beam, and the molecules to be adsorbed only on the exposed parts of the steps in direct line of sight of the evaporator. The principal attraction of the technique is its relative simplicity, as it does not involve multiple lithography steps and can be applied to metal, semiconductor or oxide surfaces alike. The technique is a "bottom-up" approach and allows great control over the separation of nanostructures within the array, as well as their individual widths. The separation is controlled by the size of the atomic terraces of the substrate, which is determined by its miscut from the principal index; and the width of the nanostructures is controlled by the oblique angle of the deposition. ATLAS has been shown to be a very versatile technique, with the growth of metallic, semi-conducting and magnetic nanowires and nanodots demonstrated using a variety of source materials and substrates. Basic Principles Figure 1(a) shows a schematic of the deposition in the "downhill" direction, that is, from an outer step edge to a lower terrace. The deposition angle β between the beam and surface is small (1°-3°) so that some areas of the terraces are exposed to the beam, and others are geometrically shadowed. The deposition angle β determines the width of the nanostructures, according to the following relation: where w is the nanostructure width, a is the height of one step, α is the miscut angle and β is the deposition angle between the incident beam and the surface (α and β are assumed to be small and are measured in radians). Figure 1(b) shows a similar situation, but this time with the substrate rotated by 180° so that the incident beam is now in the "uphill" direction, and nearly parallel to the