Faceting of nanoscale fingers on the (1 1 1) surface of gold

Gold fingers, one atomic layer (0.25 nm) high, 4-5 nm wide, and several hundred nm long are formed on the (1 1 1) surface of gold at room temperature by a combination of atomic manipulation and surface self-organisation. Each finger has two parallel edges (type A and type B, respectively) running along its length. The type A step is found to have higher step energy and become nanofaceted when disturbed by either thermal energy or the electric field under the STM tip, leading to the transformation of fingers to “nano-knives”. Our findings reveal the important role of step energy in the process of nanostructure fabrication on surfaces. The gold fingers also provide an ideal system for the investigation of meta-stable nanostructures.