Nanotube films open up new prospects for electronics 

Figure 1. Carbon nanotube film under a scanning electron microscope. Author: Skolkovo Institute of Science and Technology

Physicists from MIPT and Skoltech have found a way to modify and purposefully adjust the electronic properties of carbon nanotubes to meet the requirements of new electronic devices. The document is published in Carbon.

Carbon nanomaterials form a broad class of compounds that includes graphene, fullerenes, nanotubes, nanofibers, and more. Although the physical properties of many of these materials are already appearing in textbooks, scientists continue to create new structures and find ways to use them in real life. Macrostructures designed in the form of randomly oriented films of carbon nanotubes look like very thin cobwebs, the area of ​​which reaches several tens of square centimeters and a thickness of only a few nanometers.

Carbon nanotube films exhibit an amazing combination of physical and chemical properties such as mechanical stability, flexibility, extensibility, excellent adhesion to various substrates, chemical inertness and exceptional electrical and optical properties.

Unlike metal films, these high conductivity films are lightweight and flexible and thus can be used in a variety of electrical devices such as electromagnetic screens, modulators, antennas, balometers and so on.

Knowledge of basic physical principles is necessary for the effective use of the electrical and electrodynamic properties of films in real life. Of particular interest are terahertz and far-infrared spectral bands with wavelengths from 2 mm to 500 nm, where the films exhibit properties characteristic of metallic conductors.

Nanotube films open up new perspectives for electronics

Figure 2. Oxygen plasma treatment creates defects that alter the electrical characteristics of carbon nanotubes (left). The upper box shows the dependence of the surface resistance as a function of frequency for the treated (red curve) and intact (blue curve) films (right). The lower field shows the temperature resistance coefficients (TCR) as a function of temperature for the same films. Author: Skolkovo Institute of Science and Technology

Scientists from MIPT and Skoltech studied the conductivity of films in the terahertz and infrared ranges using films synthesized by gas-phase deposition. Some films were made of nanotubes with a length of 0.3 to 13 μm, while others were treated with oxygen plasma for 100 to 400 seconds and in the process changed their electrodynamic properties.

In a previous study, the authors proved that the conductivity of high-quality intact films can be accurately described using a conductivity model suitable for metals. In these films, the free electrons have enough energy to overcome potential barriers at the intersections of individual nanotubes and can move quite easily throughout the film, resulting in high conductivity.

However, reducing the length of the tube (up to 0.3 μm) or exposure to films in plasma (for more than 100 s) leads to a drop in conductivity at low terahertz frequencies (

When exposed to plasma for more than 100 seconds or a nanotube length below 0.3 μm TCR reaches saturation. The effect can be considered as a precursor of TCR reduction in films that are exposed to plasma for a long time, when individual tubes are severely damaged and lose their original electrical properties.

MIPT and Skoltech scientists plan to continue studying modified films, including those stretched in one or more directions. Boris Gorshunov, co-author of the work, head of the MIPT terahertz spectroscopy laboratory, comments: “Unlike nanotubes, which have long been studied in great detail, research on macro-objects such as nanotube films has only recently begun. Nanotube films are much lighter and more stable chemically and mechanically than metal films, and are therefore more attractive for use in electronics. Because we know the fundamental physics of the electrical properties of films, we can customize them for specific real-life applications. Research in the terahertz range, which will soon become ubiquitous in telecommunications, is of particular importance. ”


Physicists explain the metallic conductivity of thin films of carbon nanotubes


Additional information:
SS Zhukov et al. Terahertz-infrared spectroscopy of plates of films of single-walled carbon nanotubes processed by plasma, Carbon (2021). DOI: 10.1016 / j.carbon.2021.12.076

Provided by the Skolkovo Institute of Science and Technology

Citation: Nanotube films open new perspectives for electronics (2022, February 10), obtained February 15, 2022 from https://phys.org/news/2022-02-nanotube-prospects-electronics.html

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