A team of Stanford engineers has built a basic computer using carbon nanotubes, a semiconductor material that has the potential to launch a new generation of electronic devices that run faster, while using less energy, than those made from silicon chips

This unprecedented feat culminates years of efforts by scientists around the world to harness this promising material.

It was roughly 15 years ago that carbon nanotubes were first fashioned into transistors, the on-off switches at the heart of digital electronic systems.

But a bedeviling array of imperfections in these carbon nanotubes has long frustrated efforts to build complex circuits using CNTs.

"First, they put in place a process for fabricating CNT-based circuits," a researcher said. "Second, they built a simple but effective circuit that shows that computation is doable using CNTs."

The researcher said: "It’s not just about the CNT computer. It’s about a change in directions that shows you can build something real using nanotechnologies that move beyond silicon and its cousins."

Since mass production is the eventual goal, researchers had to find ways to deal with misaligned and/or metallic CNTs without having to hunt for them like needles in a haystack.

To eliminate the wire-like or metallic nanotubes, the Stanford team switched off all the good CNTs. Then they pumped the semiconductor circuit full of electricity. All of that electricity concentrated in the metallic nanotubes, which grew so hot that they burned up and literally vaporized into tiny puffs of carbon dioxide. This sophisticated technique was able to eliminate virtually all of the metallic CNTs in the circuit at once.

Bypassing the misaligned nanotubes required even greater subtlety.

So the Stanford researchers created a powerful algorithm that maps out a circuit layout that is guaranteed to work no matter whether or where CNTs might be askew.

The Stanford team used this imperfection-immune design to assemble a basic computer with 178 transistors, a limit imposed by the fact that they used the university’s chip-making facilities rather than an industrial fabrication process.

Though it could take years to mature, the Stanford approach points toward the possibility of industrial-scale production of carbon nanotube semiconductors, a consortium for next-generation chip design research.

This story is reprinted from material from
Stanford University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.