The world of microchip technology is on the cusp of a revolutionary advancement, and it's all thanks to the unsung heroes of our digital age: electrical interconnects. These tiny wires, typically made of copper, have been the backbone of our computers and electronic devices, but as technology advances and components shrink to the nanoscale, copper's limitations become apparent. Enter Cornell researchers, who have developed a potential replacement for copper interconnects: single-crystal nanowires of niobium arsenide. This topological semimetal has a unique property that makes it a better conductor the thinner it gets, boosting electronic performance. The findings were published in the journal Science, marking a significant step forward in the field of microchip technology.
The research, led by doctoral student Yeryun Cheon and senior author Judy Cha, the Rick and Betty Tsai Ph.D. 1981 Professor in Materials Science and Engineering, delves into the potential of topological semimetals. These materials are intriguing because extra electrons flow on the surface, in addition to the bulk, enabling nanoscale material samples to exhibit exotic properties at their surfaces and edges. Cha explains that copper's limitation lies in its bulk electrons, which start to scatter off surfaces as the wires shrink, leading to increased electrical resistance.
To address this challenge, Cha's team employed a novel process called thermomechanical nanomolding. This method allows for control over the nanowire's dimensions and morphology, a significant improvement over traditional vapor-liquid-solid growth and chemical vapor deposition techniques. By using a porous aluminum-oxide mold and pressing the material at high temperatures, the researchers can create high-quality single-crystal nanowires with diameters as small as 10 nanometers. This process is also remarkably fast, enabling the team to screen numerous materials, a tenfold increase in synthesis throughput.
One of the most exciting aspects of niobium arsenide is its robustness. Unlike many quantum materials, it remains stable at room temperature, making it less prone to oxidation. Cha believes this is a significant finding, as it suggests that quantum mechanical effects can be observed without the need for pristine samples or extreme conditions. However, Cha also acknowledges that niobium arsenide may not be a practical replacement for copper due to its toxicity, but it serves as a valuable proof of concept, demonstrating the potential of topological semimetals in real-world applications.
The research team included several co-authors, including Zhiting Tian, Mehrdad Kiani, Chen Li, and numerous doctoral students. The study was primarily supported by the Superior Energy-efficient Materials and Devices research center at Cornell, and it utilized facilities such as the Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM) and the Cornell Center for Materials Research, both supported by the NSF. This breakthrough not only showcases the potential of topological semimetals but also highlights the importance of innovative synthesis methods in advancing microchip technology.
