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takyon writes:

140nm node carbon nanotube array field-effect transistors have outperformed 90nm node silicon MOSFETs in a test:

Now, researchers at the University of Wisconsin-Madison (UW-Madison) have given SWCNTs (Single-Walled Carbon NanoTubes) a new boost in their resurgence by using them to make a transistor that outperforms state-of-the-art silicon transistors.

[...] In research described in the journal Science Advances [open, DOI: 10.1126/sciadv.1601240] [DX], the UW-Madison researchers were able to achieve a current that is 1.9 times as fast as that seen in silicon transistors. The measure of how rapidly the current that can travel through the channel between a transistor's source and drain determines how fast the circuit is. The more current there is, the more quickly the gate of the next device in the circuit can be charged.

The key to getting the nanotubes to create such a fast transistor was a new process that employs polymers to sort between the metallic and semiconducting SWCNTs to create an ultra-high purity of solution. "We've identified specific conditions in which you can get rid of nearly all metallic nanotubes, [leaving] less than 0.01 percent metallic nanotubes [in a sample]," said Arnold.

The researchers had already tackled the problem of aligning and placing the nanotubes on a wafer two years ago when they developed a process they dubbed "floating evaporative self-assembly." That technique uses a hydrophobic substrate and partially submerges it in water. Then the SWCNTs are deposited on its surface and the substrate removed vertically from the water.

Original Submission