Flexible radiofrequency carbon nanotube transistors operating at frequencies above 100 GHz

TL;DR

This paper reports the development of flexible carbon nanotube transistors capable of operating above 100 GHz, suitable for 6G wireless technology, with improved heat dissipation and high-frequency performance.

Contribution

Introduction of aligned carbon nanotube transistors on flexible substrates with electro-thermal co-design achieving over 100 GHz frequency operation.

Findings

Peak extrinsic $f_{T}$ of 152 GHz

Peak extrinsic $f_{max}$ of 102 GHz

Flexible RF amplifiers with 64 mW/mm$^{1}$ output power

Abstract

The development of the sixth generation of wireless communications technology (6G) requires terminals that can operate at frequencies above 100 GHz. For human-centric applications, these terminals should also be flexible and have low power. However, current flexible radiofrequency transistors typically have lower maximum frequencies, in part due to the poor thermal conductivity of flexible substrates. Here, we report radiofrequency transistors that are based on aligned carbon nanotube arrays on flexible substrates and have current gain cutoff frequencies ($f_{\text{T}}$) and power gain cutoff frequencies ($f_{\text{max}}$) above 100 GHz. This is achieved by using electro-thermal co-design to improve the heat dissipation and radiofrequency performance of the devices. The transistors exhibit an on-state current of 0.947 mA $\mu$m$^{-1}$, a transconductance of 0.728 mS $\mu$m$^{-1}$, a peak extrinsic $f_{\text{T}}$ of 152 GHz, a peak extrinsic $f_{\text{max}}$ of 102 GHz, and a power consumption under 200 mW mm$^{-1}$. We also show that the devices can be used to create flexible radiofrequency amplifiers with an output power of 64 mW mm$^{-1}$ and a 11 dB power gain in the K-band.