Cornell Scientists Discover Niobium Arsenide Nanowires Outperform Copper in Microchip Conductivity

Cornell Scientists Discover Niobium Arsenide Nanowires Outperform Copper in Microchip Conductivity

Researchers at Cornell University have developed nanowires made from niobium arsenide (NbAs), a topological quantum material with properties that stand in stark contrast to copper: as the wires shrink in size, their electrical conductivity actually improves. The discovery positions NbAs as a promising candidate to replace copper in next-generation microchip interconnects.

Electrical interconnects — the microscopic wires and connectors that link transistors within electronic systems — are critical to modern chip performance and are currently manufactured primarily from copper. However, as chips continue to scale down to nanometer dimensions, copper's conductivity degrades and its electrical resistance rises, creating a fundamental barrier to further miniaturization.

Rethinking the Limits of Copper Wiring

Copper has long been the dominant material for processor interconnects thanks to its excellent conductivity. The semiconductor industry made the switch from aluminum to copper in the late 1990s, with IBM leading that transition in 1997.

At nanoscale dimensions, however, electrons increasingly collide with the surface of copper wires, causing resistance to spike and efficiency to fall. This is the core physical limitation copper faces at extremely small sizes.

Niobium Arsenide: The Advantage of Surface Electrons

To overcome this bottleneck, the Cornell team turned to niobium arsenide (NbAs) — a topological semimetal in which surface electrons behave very differently from those in conventional metals.

"The electrons that travel along the surface of the material move very fast and don't scatter as easily as electrons inside the material," said Dr. Judy Cha, professor of materials science and senior author of the study.

She explained that in copper, as wires get thinner, electrons collide more frequently with surfaces and scatter in all directions, causing conductivity to plummet — "that's why copper becomes highly resistive."

NbAs, by contrast, conducts current primarily through high-velocity surface electrons. The thinner the wire, the greater the surface-to-volume ratio, and the better the electrical performance.

Thermomechanical Nanomolding: Like Making Pasta

To fabricate these ultra-thin wires, the research team employed a process called thermomechanical nanomolding. In simple terms, bulk niobium arsenide is pressed under high temperature into a porous aluminum oxide mold. Once the mold is removed, the result is a high-quality single-crystal nanowire that can be transferred onto a silicon wafer.

The technique enables precise control of wire diameter down to 10 nanometers (nm).

Cha used pasta-making as an analogy: "Change the die plate on a pasta machine and you can make fettuccine or angel hair. We're just using the bulk material as 'dough' and swapping in molds with different pore sizes."

Beyond producing highly uniform nanowires, the method has also dramatically accelerated the pace of materials research. The lab previously studied one or two material systems per year; with thermomechanical nanomolding, it can now explore a new material every month.

Room-Temperature Stability: A Key Breakthrough for Quantum Materials

The team also found that NbAs nanowires remain stable at room temperature — a significant advantage, as many quantum materials tend to oxidize or degrade outside tightly controlled laboratory conditions.

"I think that's the real significance of this work," Cha said in a press release. "You don't need the highest-purity sample, and you don't need to be in the coldest, most noise-free environment to observe these kinds of quantum mechanical effects."

The research has been published in the peer-reviewed journal Science.

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