Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Future Electronics Based on Carbon Nanotubes

08.04.2015

A team at the University of Illinois at Urbana-Champaign finds way to purify arrays of single-walled carbon nanotubes (SWCNTs), possibly providing a step toward post-silicon circuits and devices

The exceptional properties of tiny molecular cylinders known as carbon nanotubes have tantalized researchers for years because of the possibility they could serve as a successors to silicon in laying the logic for smaller, faster and cheaper electronic devices.


J.Rogers/UIUC

Thermal gradients associated with mild heating of a metallic carbon nanotube induces thermocapillary flows in a thin organic overcoat. The result is an open trench with the tube at the base.

First of all they are tiny -- on the atomic scale and perhaps near the physical limit of how small you can shrink a single electronic switch. Like silicon, they can be semiconducting in nature, a fact that is essential for circuit boards, and they can undergo fast and highly controllable electrical switching.

But a big barrier to building useful electronics with carbon nanotubes has always been the fact that when they're arrayed into films, a certain portion of them will act more like metals than semiconductors -- an unforgiving flaw that fouls the film, shorts the circuit and throws a wrench into the gears of any potential electronic device.

In fact, according to University of Illinois-Urbana Champaign professor John Rogers, the purity needs to exceed 99.999 percent -- meaning even one bad tube in 100,000 is enough to kill an electronic device. "If you have lower purity than that," he said, "that class of materials will not work for semiconducting circuits."

Now Rogers and a team of researchers have shown how to strip out the metallic carbon nanotubes from arrays using a relatively simple, scalable procedure that does not require expensive equipment. Their work is described this week in the Journal of Applied Physics, from AIP Publishing.

The Road to Purification

Though it has been a persistent problem for the last 10-15 years, the challenge of making uniform, aligned arrays of carbon nanotubes packed with good densities on thin films has largely been solved by several different groups of scientists in recent years, Rogers said.

That just left the second problem, which was to find a way to purify the material to make sure that none of the tubes were metallic in character -- a thorny problem that had remained unsolved. There were some methods of purification that were easy to do but fell far short of the level of purification necessary to make useful electronic components. Very recent approaches offer the right level of purification but rely on expensive equipment, putting the process out of reach of most researchers.

As the team reports this week, they were able to deposit a thin coating of organic material directly on top of a sheet of arrayed nanotubes in contact with a sheet of metal. They then applied current across the sheet, which allowed the current to flow through the nanotubes that were metal conductors -- but not the bulk of the tubes, which were semiconducting.

The current heated up the metal nanotubes a tiny amount -- just enough to create a "thermal capillary flow" that opened up a trench in the organic topcoat above them. Unprotected, the metallic tubes could then be etched away using a standard benchtop instrument, and then the organic topcoat could be washed away. This left an electronic wafer coated with semiconducting nanotubes free of metallic contaminants, Rogers said. They tested it by building arrays of transistors, he said.

"You end up with a device that can switch on and off as expected, based on purely semiconducting character," Rogers said.

The article, “Direct current injection and thermocapillarity flow for purification of aligned arrays of single-walled carbon nanotubes,” is authored by Xu Xie, Muhammad A. Wahab, Yuhang Li, Ahmad E. Islam, Bojan Tomic, Jiyuan Huang, Branden Burns, Eric Seabron, Simon N. Dunham, Frank Du, Jonathan Lin, William L. Wilson, Jizhou Song, Yonggang Huang, Muhammad A. Alam and John A. Rogers. It appears in the Journal of Applied Physics on April 7, 2015 (DOI: 10.1063/1.4916537). After that date, it can be accessed at: http://scitation.aip.org/content/aip/journal/jap/117/13/10.1063/1.4916537

The researchers on this paper are affiliated with the University of Illinois at Urbana-Champaign; Purdue University in West Lafayette, Indiana; Beihang University in Beijing, China; Zhejiang University in Hangzhou, China; and Northwestern University in Evanston, Illinois.

ABOUT THE JOURNAL

Journal of Applied Physics is an influential international journal publishing significant new experimental and theoretical results of applied physics research. See: http://jap.aip.org

Contact Information
Jason Socrates Bardi
+1 240-535-4954
jbardi@aip.org
@jasonbardi

Jason Socrates Bardi | newswise

Further reports about: AIP Applied Physics Nanotubes carbon nanotubes circuit expensive metallic purification semiconducting tiny tubes

More articles from Physics and Astronomy:

nachricht Molecule flash mob
19.01.2017 | Technische Universität Wien

nachricht Magnetic moment of a single antiproton determined with greatest precision ever
19.01.2017 | Johannes Gutenberg-Universität Mainz

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Global threat to primates concerns us all

19.01.2017 | Ecology, The Environment and Conservation

Scientist from Kiel University coordinates Million Euros Project in Inflammation Research

19.01.2017 | Awards Funding

The Great Unknown: Risk-Taking Behavior in Adolescents

19.01.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>