Researchers Grow Self-Aligned Nanotubes

KingFish

Growing carbon nanotubes on silicon could enable nanoscale transistors, but only if designers can specify exactly where the tiny devices grow. Engineers at Case Western Reserve University have demonstrated how to grow nanotubes exactly where designers want them — self-aligned across a wafer.

The researchers also reported that the nanotubes self-welded during growth, and claimed that their nanotube-enabled wafers need only to be diced and wire-bonded to a chip carrier. This would make them as reliable and cost effective as current chips.

"Our contribution has been to come up with a technique where the nanotubes grow where you want them to grow — between two electrical posts," said Massood Tabib-Azar, a professor in the electrical engineering department at Case Western (Cleveland).

Others have experimented with nanotube-based transistors, but have usually studied them where they happened to be located on a substrate. Some experiments have harnessed electric fields to grow nanotubes in selected locations, but that technique is not scalable across a wafer.

Case Western's method, on the other hand, aims to locate nanotubes where they are required on a chip and scale the process across a wafer so nanotubes grow simultaneously and weld themselves in place.

"The self-welding is the really critical breakthrough," said Tabib-Azar. "They grow from one post to the other post, and when they reach the other post they weld themselves to it."

Source: EE Times

TheBaron

does anyone know how a nanotube would actually function in a transistor configuration? I can't really see how you could make a MOSFET with one of these, or a BJT. would you need a new transistor type?

deicist

From the article:

The multi-walled carbon nanotubes being grown exhibit p-type conductivity

From Google:

http://www.semiconfareast.com/whatissemicon.htm

When a p-type semiconductor region is placed adjacent to an n-type region, they form a diode, and the region of contact is called a p-n junction.

The p-n junction is the most basic building block of semiconductor electronics.

Basically the nanotubes behave like semi-conductors and semi-conductors can be used to make transistors. MOSFETs, BJTs and other types of transistor differ in their practical application, but the principles are the same.

TheBaron

I should have just read the article, I didn't know it behaved like a p-type material (although It'd be interesting to know why it does that, I thought it was a charge neutral device)