Fabrication of extremely narrow metal wires

A robust technique for fabrication of metal wires with controlled widths substantially below 10 nm is presented. By etching a cleaved molecular-beam epitaxy grown substrate, a mechanical template is produced with surface relief of atomic lateral definition. Using metal deposition and directional ion etching of such a substrate, electrically continuous wires are formed from AuPd alloy with diameters as small as 3 nm and lengths greater than 1 μm. This technique can be used with a variety of materials and makes metallic nanostructures on a previously inaccessible size scale.