Science 335, 64–67 (2012)

In this digital age, electronic hardware is being packed into ever smaller spaces. Now Bent Weber and co-workers have shown that one of the most fundamental rules governing electrical flow — Ohm's law — still applies in wires that are just a few atoms in diameter.

Narrower wires have a greater surface area to volume ratio. This, in turn, increases the influence of surface defects, which disrupt the flow of electrons and increase the resistivity of the wire. Weber et al., however, show that they can create 'interface-free' wires by embedding phosphorous atoms in a silicon crystal.

The team used the latest lithographic techniques to write their dopant wires, which were then covered by more silicon. Although the wires were just one atom in height and four atoms in width, they still had an electrical resistivity of the same order as bulk materials. This result shows that, despite decades of miniaturization, there is still scope for further generations of electronic circuitry.