Researchers in Japan, including the University of Tokyo, have created ~1 nm-wide semiconducting nanotubes—about 100,000× thinner than a human hair—by growing molybdenum disulfide inside boron nitride tubes to form stable, uniform structures at an extreme scale. The results validate long-standing theoretical predictions about ultrathin nanotube behavior and may open new possibilities for ultra-miniaturized electronics.
The study was published in the journal Science.
New Nanotubes Offer Advantages Over Carbon
While carbon nanotubes previously drew significant attention, a newer material is now emerging with potential advantages that may encourage engineers to build future devices around it.
Molybdenum disulfide (MoS₂) nanotubes, still at an experimental stage, show promise for use in semiconductor electronics, high-resolution sensing, and research in quantum-scale physics.
We successfully synthesized atomically precise semiconducting nanotubes with nanometer-scale diameters. The coaxial design, with MoS₂ nanotubes encased in insulating boron nitride, is promising for advanced gate-all-around transistors, said University of Tokyo’s Associate Professor Yusuke Nakanishi.
“Our study shows a method for precisely controlling the structure of inorganic semiconducting nanotubes at the atomic level. We also experimentally confirmed that the bandgap—which determines how a material behaves as a semiconductor—decreases as the nanotube diameter becomes smaller, matching theoretical predictions made over 25 years ago.”
In contrast, traditional nanotube fabrication techniques typically produce structures larger than 10 nanometers, often with multiple concentric walls and irregular or poorly controlled atomic arrangements.
Precise 1-Nm MoS₂ Nanotubes via Confined Growth
Nakanishi and his team created 1-nm-wide single-walled MoS₂ nanotubes with precise atomic structure by growing them inside boron nitride nanotubes, whose confined space helps stabilize and organize the otherwise hard-to-form nanotubes for device use.
In nanotubes, even minor structural variations can significantly influence their properties. When researchers precisely control the structure, they achieve more uniform properties, which are essential for reliable and reproducible transistor performance. The key advantage is atomic-level structural precision, Nakanishi explained.
“By contrast, manufacturers typically fabricate modern silicon transistors by etching bulk silicon. However, as device sizes shrink, they face increasing difficulty maintaining perfect structures because even small defects can have a large impact.”
“Carbon nanotubes also present challenges for transistor use, because even very small structural variations can significantly alter their behavior, including whether they act as metals or semiconductors. In contrast, our nanotubes may provide a more dependable approach for creating ultra-small semiconductor channels with consistent properties.”
Key Challenges Remain Before Practical Transistor Use
However, practical devices are still several years away, and key obstacles must be overcome before functional transistors can be built. One major goal is to extend nanotube length from a few hundred nanometers to about 1 micrometer (1,000 nanometers, or one-thousandth of a millimeter).
Looking ahead, the technique could also be applied to other inorganic nanotubes, including magnetic and superconducting materials. The researchers aim to expand nanotube research beyond carbon systems, enabling atomically precise nanotubes for research, sensing, and advanced miniaturized high-speed electronics.
Read the original article on: phys.org
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