Carbon nanotube tech exceeds 100 GHz in RF applications

Start-up company Carbonics recently partnered with the University of Southern California (USC) to develop a carbon nanotube technology that has successfully achieved speeds exceeding 100 GHz in radiofrequency applications.

Published in the journal Nature Electronics and partially funded by the US Army Research Office, the milestone is said to eclipse the performance — and efficiency — of the traditional radiofrequency complementary metal-oxide semiconductor (RF-CMOS) technology that is ubiquitous in modern consumer electronics, including mobile phones, and opens the door for this new technology to potentially provide a powerful boost for 5G and mm-Wave technologies.

For nearly two decades, researchers have theorised that carbon nanotubes would be suitable as a high-frequency transistor technology due to their unique one-dimensional electron transport characteristics. Indeed, projections based on scaling single carbon nanotube device metrics suggest the technology could ultimately far exceed the top-tier incumbent RF technology, gallium arsenide (GaAs). The engineering challenge has been to assemble the high-purity semiconducting nanotubes into densely aligned arrays and create a working device out of the nanomaterial.

Carbonics employs a deposition technology called ZEBRA that enables carbon nanotubes to be densely aligned and deposited onto a variety of chip substrates including silicon, silicon-on-insulator, quartz and flexible materials. This allows the technology to be directly integrated with traditional CMOS digital logic circuits, overcoming the typical problem of heterogeneous integration.

“With this exciting accomplishment, the timing is ripe to leverage our CMOS-compatible technology for the 5G and mm-Wave defence communication markets,” said Carbonics CEO Kos Galatsis. “We are now engaged in licensing and technology transfer partnerships with industry participants, while we continue to advance this disruptive RF technology.”

“This milestone shows that carbon nanotubes, long thought to be a promising communications chip technology, can deliver,” added Dr Joe Qiu, Program Manager at the Army Research Office. “The next step is scaling this technology, proving that it can work in high-volume manufacturing. Ultimately, this technology could help the Army meet its needs in communications, radar, electronic warfare and other sensing applications.”

Image caption: Carbonics’ carbon nanotube technology is made up of semiconducting aligned carbon nanotubes (the transparent lattice tubes at the bottom of the image) within a transistor device structure. The quasi ballistic transport within the carbon nanotubes acts as a super highway for electrons to speed through the device resulting in a superfast and linear radiofrequency technology. Image courtesy Carbonics.

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