Formation of electrically conducting mesoscale wires through self-assembly of atomic clusters

Bi and Sb clusters deposited from an inert gas aggregation source have been used to form cluster-assembled wires on unpassivated, and SiO₂ passivated, V-grooved Si substrates. V-grooves (4-7 μm in width, 6 μm-1 mm in length) were prepared using optical lithography and anisotropic etching in KOH solution. The effectiveness of the surface templating technique was demonstrated by scanning electron microscope analysis carried out after deposition. When Sb clusters were deposited onto SiO₂ passivated substrates, the surface coverage was seen to vary from <20% on the unpatterned (normal-to-beam) surface (which is required to be nonconducting) to >100% at the apexes of the V-grooves used to promote growth of the wire. Sb wires produced with this technique currently have minimum widths of ∼400 nm and lengths of ∼1 mm. Electrical contacts can be positioned within the V-grooves prior to cluster deposition, thus enabling the initial onset of conduction and subsequent I(V) characteristic of a wire to be monitored in vacuum.