Nanowires self-assemble into custom arrangements
Tokyo Metropolitan University researchers have developed a technique to make self-assembled nanowires at scale – and tune their arrangement – using chemical vapour deposition (CVD).
In order to continue miniaturising electronics, packing more computing power into the same amount of space, it is necessary to create smaller and smaller wiring and components.
A hypothetical atom-thick wire, for instance, would be the ultimate goal. This could give rise to new categories of electronic and energy devices, as the electrons travelling through them would behave more as though they are moving through a one-dimensional world than a three-dimensional world.
Scientists can already transform materials like carbon nanotubes and transition metal chalcogenides (TMCs), mixtures of transition metals and group 16 elements which can self-assemble into atomic-scale nanowires. These have three-atom diameters (with chalcogen atoms occupying three corners of a triangular-like frame and metal atoms in the middle of each side) and van der Waals surfaces, and have been reported to possess a one-dimensional metallic nature.
Although TMCs were discovered 40 years ago, creating them at scale and at useful lengths is still a challenge and mass production of nanowires has so far remained out of reach.
Now, a Tokyo Metropolitan University team has developed a method for creating long wires of transition metal telluride nanowires at unprecedented scales.
Using CVN, they can assemble these nanowires into different configurations depending on the substrate they use as a template. Adjusting the structure of the substrate allowed the researchers to create centimetre-sized wafers covered in arrangements including atomically-thin sheet-like monolayers, bilayers, and random networks of bundles of wires, all with different applications.
The structure of the nanowires themselves were highly crystalline and ordered, and their properties (including excellent conductivity and one-dimensional-like behaviour) matched those predicted by theory.
Producing large quantities of long, crystalline nanowires will be valuable for further research into these structures, which has so far been restricted due to scarcity of TMC nanowire samples. It also marks an important step towards real-world nanowire applications.
“The ability to achieve large-scale synthesis and manipulate the nanowire growth direction is important, as it provides a possible means for scalable, direct orientation patterning of TMC nanowires via surface engineering,” the researchers wrote in their Nano Letters paper. “The present findings offer a new platform for novel studies and applications of [one-dimensional] nanowire systems, contributing not only to new discoveries in basic low-dimension physics but also to the design of future applications in electronics and energy storage/conversion devices.”
Header image does not depict the nanowire arrangements created in this study.
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