Carbon nanotubes are about to dethrone silicon chips and reinstate Moore’s law


Original news release was issued by American Technion Society, written by Kevin Hattori.

The next step in electronic design is clear as day. With silicon chips reaching their limit, development of carbon nanotubes may be about to usher us in the age of molecular electronics.

Our electronics, powered by silicon chips, are quickly reaching their limit, as chips smaller than 5nm will simply overheat. That raises question marks around Moore’s law, which has, since its formulation in 1965, become a tent pole that guides the market of digital electronics. Many researchers are hard at work to develop an alternative to silicon and it has been pretty clear for a while that carbon nanotubes (CNTs) will be the way to go because of their unprecedented electrical, optical, thermal and mechanical properties.

But due to the nanometer size of the CNTs (100,000 times smaller in diameter than the thickness of a human hair) it is very tricky to build uniform CNTs on a large scale. As stated by the leader of the research team, Prof. Yuval Yaish of the Viterbi Faculty of Electrical Engineering, “Current methods for the production of CNTs are slow, costly, and imprecise. As such, they generally cannot be implemented in industry.” Better methods for CNT growing are necessary before we can take the leap in computing, which is precisely what Yaish and his team have done.

Preferential adsorption of p-nitrobenzoic acid on carbon nanotubes. (a) Top: Chemical structure of p-nitrobenzoic acid (pNBA). Bottom: Schematic illustration of the monoclinic unit cell of pNBA powder as extracted from X-ray diffraction analysis. (b,c) Dark field optical microscopy images of pNBA nanocrystals adsorbed along CVD grown carbon nanotubes (CNTs). Scale bar, 50 and 20 µm, respectively. (d) Amplitude image of AFM of a single CNT with a few pNBA nanocrystals along. Scale bar, 1 µm. Inset: height cross sections along the marked lines of the main figure. (e) Dark field optical microscopy image of pNBA nanocrystals after intensive deposition. Note the black voids along the CNT. Scale bar, 20 µm. (f) Dark field optical microscopy image of pNBA nanocrystals adsorb onto commercial dispersed CNTs. Scale bar, 20 µm. (Source: ATS)

They have developed a simple, rapid, non-invasive and scalable technique that enables optical imaging of CNTs. Instead of depending upon the CNT chemical properties to bind marker molecules, the researchers relied on the fact that the CNT is both a chemical and physical defect on the otherwise flat and uniform surface. It can serve as a seed for the nucleation and growth of small, but optically visible nanocrystals, which can be seen and studied using a conventional optical microscope. Since the CNT surface is not used to bind the molecules, they can be removed completely after imaging, leaving the surface intact, and preserving the CNT’s electrical and mechanical properties.

“Our approach is the opposite of the norm,” Yaish continued. “We grow the CNTs directly, and with the aid of the organic crystals that coat them, we can see them under a microscope very quickly. Then image identification software finds and produces the device (transistor). This is the strategy. The goal is to integrate CNTs in an integrated circuit of miniaturized electronic components (mainly transistors) on a single chip (VLSI). These could one day serve as a replacement for silicon electronics.”

Michal Dudic

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