Over the past decades, electronics engineers worldwide have been trying to develop devices that could enable even faster communications between devices, all while consuming less energy. To meet the demands of the sixth generation (6G) of wireless communication technology, these devices should operate at frequencies above 100 gigahertz (GHz).
So far, developing flexible electronic components that can operate at these high frequencies while consuming little power has proved challenging. One promising approach for fabricating these devices entails the use of carbon nanotubes (CNTs), extremely thin and cylindrical structures with advantageous electrical and thermal properties.
Researchers at Peking University and Stanford University recently developed new flexible and low-power CNT-based transistors that operate at frequencies above 100 GHz. These transistors, presented in a paper published in Nature Electronics, could potentially help to speed up communications between future smartphones, sensors, wearable devices, and other flexible devices.
“This work was inspired by the need for future wireless systems that are not only faster, but also flexible, lightweight and suitable for human-centric applications such as wearable or body-integrated devices,” Youfan Hu, co-senior author of the paper, told Tech Xplore. “Carbon nanotubes have already shown excellent radio-frequency (RF) performance on rigid substrates, so we saw flexible CNT-based RF electronics as a promising route to meet this need, but need to address the thermal limitations that usually arise in flexible electronics.”
New RF transistors based on carbon nanotubes
The central goal of this recent study was to successfully fabricate new low-power RF transistors that operate above 100 GHz using CNTs. RF transistors are electronic components that support wireless communications, by generating, amplifying, or switching electronic signals oscillating at radio frequencies.
“More broadly, we wanted to devise a general design framework for flexible RF electronics, showing that device scaling, parasitic control, and heat dissipation must be optimized together to fully realize the potential of advanced materials on flexible substrates,” said Hu. “Our transistors work like extremely fast switches or amplifiers. The electrical current flows through aligned carbon nanotubes, and a gate electrode controls that current at radio frequencies.”
The transistors fabricated by Hu and her colleagues are built on a thin and flexible polyamide substrate, allowing them to bend and conform to non-planar surfaces. Importantly, in bending tests, the devices retained most of their high-speed radio-frequency performance.
A key challenge when trying to develop smaller transistors that operate at frequencies above 100 GHz is heat. Specifically, when a transistor’s dimensions are reduced, its internal temperature can increase significantly, particularly if it is based on flexible materials that do not conduct heat as well as silicon.
“We addressed this challenge with a new electro-thermal co-design, engineering the transistor structure and materials to balance high-frequency performance and heat dissipation,” explained Eric Pop, co-senior author of the paper. “For example, thicker contacts improve cooling but can also hurt high-frequency performance, and carefully balancing these trade-offs was a key part of the design.”
Contributing to the advancement of communication systems
In initial tests, the new RF transistors developed by Hu, Pop, and their collaborators were found to achieve very promising results. Specifically, they yielded a peak current-gain cut-off frequency of 152 GHz and a peak power-gain cut-off frequency of 102 GHz, all while maintaining a low power consumption under 200 mW mm?1.
“Flexible substrates trap heat much more easily than rigid silicon, which makes high-performance flexible electronics more difficult to achieve,” said Pop. “Thus, a key finding in this work was that the thermal design cannot be ignored when designing high-performance circuits on flexible substrates. Rather, this must be included during the stage of device design. This has allowed us to achieve flexible transistors operating above 100 GHz with low power consumption, for the first time.”
In the future, the new design strategy introduced by this research team could be adapted and used to develop other low-power CNT-based electronic components compatible with the next-generation of wireless communication technology. Meanwhile, Hu, Pop, and their colleagues will try to further improve the speed, reliability, and system-level integration of their flexible CNT RF transistors.
“Our next efforts will include improving substrate engineering for heat dissipation, combining mechanical and electrothermal co-design for improved robustness under bending, and further optimizing the transistor structure,” added Hu. “Ultimately, we hope to move from individual high-performance transistors toward complete flexible RF systems that integrate CNT circuits with antennas, sensors, and digital or analog circuits for next-generation wireless and wearable technologies.”
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Publication details
Fan Xia et al, Flexible radio-frequency carbon nanotube transistors operating at frequencies above 100?GHz, Nature Electronics (2026). DOI: 10.1038/s41928-026-01632-1.
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