Spontaneous Assembly of Ordered Atomic Wires with a Long Interwire Distance on a Stepped Atomic Template

Indium atomic wires with a long interwire distance of 5.73 nm were ordered spontaneously at room temperature on a stepped atomic template using a Si(557) surface. The long interwire distance is very interesting because, in general, interwire interactions are needed to order atomic wires in such a way that ordered atomic wires have a short interwire distance of just a few Å. The Si(557) surface is composed of four steps, i.e., one (111) step and three (112) steps, with a very similar local structure to each other. However, mobile indium atoms at room temperature were adsorbed specifically onto the second Si(112) step while maintaining the overall structure of the stepped atomic template, as observed by scanning tunneling microscopy, which results in the ordered atomic wires with the long interwire distance. This was supported by first-principles calculations.