Nano-size computer hailed as breakthrough

Deutsche Welle, 27 Sep 2013

Scientists in California say they have built a functioning microscopic computer made of carbon "nanotubes" instead of silicon. The step could lead to faster, ever-smaller electronic devices.

Stanford University researchers said they have overcome downsizing limits posed by silicon transistors in everyday computers by using tiny semiconductors from rolled-up arrays of carbon atoms called "nanotubes" in a basic computer.

Carbon nanotubes are rolled-up, single-layer sheets of carbon atoms. Tens of thousands can fit into the width of a single human hair.

The minute prototype using several thousand carbon nanotubes (CNTs) was able to perform basic counting and number-sorting functions, said engineering professor Subhasish Mitra.

"People have been talking about a new of carbon nanotube (CNT) electronics moving beyond silicon," Mitra said. "Here is the proof."

Manufacture possible

A Stanford University announcement - also covered by the journal Nature - quoted the director of a computer chip design consortium, Naresh Shanbhag, as saying that industrial-scale production of the CNT semiconductors was possible within years.

Another Stanford project leader, Philip Wong, said carbon nanotubes used less power and were smaller than silicon circuits.

"CNT's could take us at least an order of magnitude in performance beyond where you can project silicon could take us."

He was referring to a postulate first raised in 1965 that manufacturers can double the density of silicon transistors roughly every two years, but only down to 5 nanometers. Silicon's limit is expected to be reached around 2020.

Furthermore, silicon transistors packed onto conventional chips generate more heat and waste power.

Stanford University said its researchers had achieved an "unprecedented feat" with the nanotube technology, which has been around for 15 years, by also creating a "powerful algorithm" to handle imperfections in the carbon tunnels and map out a circuit. This was "guaranteed to work no matter whether or where CNTs might be askew," the university said.

'Significant advance'

German hybrid electronics expert, Frank Kreupl of the Munich's Technical University commented in the Nature edition that the Stanford nanotube computer represented a significant advance.

He added, however, that the CNT transistors would have to become even smaller for the technique to be feasible and the processors quicker.

ipj/hc (AFP, dpa)