[News] World’s Smallest Semiconductor Nanotube Achieved at 1 Nanometer
A research team led by the The University of Tokyo has fabricated the world’s smallest semiconductor nanotube, according to a study published in the latest issue of Science. Using boron nitride (BN) nanotubes as a template, the researchers successfully synthesized single-walled molybdenum disulfide (MoS₂) nanotubes with a diameter of just 1 nanometer—roughly one hundred-thousandth the width of a human hair.
The achievement not only validates theoretical predictions about the electronic properties of ultrafine materials made decades ago, but also opens new possibilities for the development of next-generation miniaturized electronic devices.
Carbon nanotubes have long attracted attention for their exceptional mechanical and electrical properties. However, slight variations in their atomic structure can significantly alter their conductivity, posing challenges for transistor applications. In contrast, MoS₂ is an intrinsically semiconducting material with promising potential for semiconductor electronics, high-sensitivity sensing, and quantum-scale physics research. Yet producing ultrathin, structurally controlled MoS₂ nanotubes has remained a major challenge, as stability and fabrication complexity increase dramatically as nanotube diameters shrink.
To overcome these limitations, the researchers carried out chemical reactions within the confined interior of BN nanotubes, creating single-walled MoS₂ nanotubes with a well-defined atomic structure and a diameter of only 1 nanometer. According to the team, the restricted space inside the BN nanotubes enabled the growth of ultrafine MoS₂ nanotubes that would otherwise be difficult to form, while also promoting ordered atomic arrangement and high structural uniformity.
The study found that the bandgap of the nanotubes decreases as their diameter becomes smaller, confirming a theoretical prediction first proposed 25 years ago.
Conventional nanotube fabrication techniques typically produce multi-walled nanotubes with diameters exceeding 10 nanometers, while precise control over atomic structure remains difficult. At the nanoscale, even minute structural variations can have a substantial impact on material performance, making atomic-level structural control essential for future device applications.
Existing semiconductor technologies face increasing challenges in maintaining structural perfection as device dimensions continue to shrink, with defects exerting a growing influence on performance. Carbon nanotubes encounter similar issues. Researchers believe that MoS₂ nanotubes may offer advantages in terms of dimensional control and atomic-scale uniformity, potentially providing a new pathway toward ultra-small semiconductor channels.
Despite the breakthrough, practical applications remain some distance away. The nanotubes produced in the current study are only a few hundred nanometers long. The team’s next goal is to extend their length to approximately 1 micrometer (1,000 nanometers) and explore the fabrication of other inorganic nanotube materials using the same approach, including magnetic and superconducting materials.
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