Computational nanotech studies have shown that deliberate introduction of structural defects at specific sites in carbon nanotubes can guide electrons along specific paths, providing a way to fabricate complex electronic circuits from nanotubes. Although this research was theoretical, the researchers are quoted as saying focused electron beams could be used to create the defects where they would be needed to make complicated networks. An item on KurzweilAI.net led to this article on New Scientist Tech, written by Colin Barras. From “Flawed nanotubes could be perfect silicon replacement“:
The paradox of perfection — that flaws make things perfect — could be the key to designing nanoelectronic circuits from carbon nanotubes, according to US scientists.
They have discovered that a circuit of nanotubes can only guide a current if some of the tubes carry structural defects.
Individual carbon nanotubes are exceptionally good conductors because they are essentially a single carbon molecule. They can even outdo silicon at transmitting charge, which means nanotube circuits could boost computing speeds while reducing chip size…
But connecting nanotubes into such circuits is not easy, says Vincent Meunier at Oak Ridge National Laboratory in Tennessee. “The connections between individual nanotubes do not conduct well,” he says.
Instead of jumping easily into an adjacent nanotube, as they would between metal wires, electrons are more likely to bounce back when they reach the end of a tube, says Meunier. Electrons treat junctions between nanotubes as barriers — what scientists call “opaque”.
Now Meunier’s team has discovered that it could improve the transparency of the junctions by adding flaws to the connecting ends of nanotubes.
The carbon atoms within a nanotube are normally arranged in a hexagonal lattice similar to chicken wire. But the researchers used detailed simulations to see what happens when a few pentagons and heptagons are added to the otherwise regular structure.
The research was published in ACS Nano (abstract).
—Jim
