Nanotubes Solder Themselves, Paving the Way for More Efficient Transistors (VIDEO)

By  Nov 26, 2013 11:07 AM EST
Carbon nanotubes could solder themselves.
Carbon nanotubes could solder themselves.

Researchers have found a way to repair gaps in nanowires that are too small for even the tiniest tools.

 These nanotubes are made from carbon, and are only about one atom thick, a University of Illinois news release reported.

Researchers are looking to use to miniscule devices as transistors as a replacement for silicon because they are easier to transport onto substrates like plastic sheets to create more economical electronics.

Carbon nanotubes are naturally "high-quality conductors"; but it is still a very difficult task to create only one nanotube to use as a transistor. It is much more viable to create a system of nanotubes where the current jumps between wires and set junctions.

If this process was being carried out in larger wires they would be soldered, but since the nanowires were so tiny researchers had to come up with an alternative.

"It occurred to me that these nanotube junctions will get hot when you pass current through them," electrical and computer engineering professor Joseph Lyding said. "Kind of like faulty wiring in a home can create hot spots. In our case, we use these hot spots to trigger a local chemical reaction that deposits metal that nano-solders the junctions."

In the nano-soldering process a carbon nanotube is put in a chamber containing metal-containing gas molecules. The resistance of the electrons flowing through the transistors causes the junctions to heat. The molecules then react to the heat, depositing metal at the hotspots and essentially "soldering" them. Once the area is soldered the resistance and temperature drops, putting a stop to the soldering reaction.

The process is simple, quick, and causes the resistor to function almost as well as it would with only one nanotube.

"It would be easy to insert the CVD process in existing process flows," Lyding said. "CVD technology is commercially available off-the-shelf. People can fabricate these transistors with the ability to turn them on so that this process can be done. Then when it's finished they can finish the wiring and connect them into the circuits. Ultimately it would be a low-cost procedure."

The team hopes to make the process even more efficient.

"We think we can make it even better," Lyding said. "This is the prelude, we hope, but it's actually quite significant."


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