For instance, these tiny cylinders of carbon molecules theoretically can carry 1,000 times more electric current than a metal conductor of the same size. It's easy to imagine carbon nanotubes replacing copper wiring in future nanoscale electronics.
Micrograph of recession and clumping in gold electrodes after NIST researchers applied 1.7 volts of electricity to the carbon nanotube wiring for an hour. The NIST reliability tests may help determine whether nanotubes can replace copper wiring in next-generation electronics. Credit: M. Strus/NIST
But—not so fast. Recent tests at the National Institute of Standards and Technology (NIST) suggest device reliability is a major issue.
Copper wires transport power and other signals among all the parts of integrated circuits; even one failed conductor can cause chip failure. As a rough comparison, NIST researchers fabricated and tested numerous nanotube interconnects between metal electrodes. NIST test results, described at a conference this week,* show that nanotubes can sustain extremely high current densities (tens to hundreds of times larger than that in a typical semiconductor circuit) for several hours but slowly degrade under constant current. Of greater concern, the metal electrodes fail—the edges recede and clump—when currents rise above a certain threshold. The circuits failed in about 40 hours.
While many researchers around the world are studying nanotube fabrication and properties, the NIST work offers an early look at how these materials may behave in real electronic devices over the long term. To support industrial applications of these novel materials, NIST is developing measurement and test techniques and studying a variety of nanotube structures, zeroing in on what happens at the intersections of nanotubes and metals and between different nanotubes. "The common link is that we really need to study the interfaces," says Mark Strus, a NIST postdoctoral researcher.
In another, related study published recently,** NIST researchers identified failures in carbon nanotube networks—materials in which electrons physically hop from tube to tube. Failures in this case seemed to occur between nanotubes, the point of highest resistance, Strus says. By monitoring the starting resistance and initial stages of material degradation, researchers could predict whether resistance would degrade gradually—allowing operational limits to be set—or in a sporadic, unpredictable way that would undermine device performance. NIST developed electrical stress tests that link initial resistance to degradation rate, predictability of failure and total device lifetime. The test can be used to screen for proper fabrication and reliability of nanotube networks.
Despite the reliability concerns, Strus imagines that carbon nanotube networks may ultimately be very useful for some electronic applications. "For instance, carbon nanotube networks may not be the replacement for copper in logic or memory devices, but they may turn out to be interconnects for flexible electronic displays or photovoltaics," Strus says.
Overall, the NIST research will help qualify nanotube materials for next-generation electronics, and help process developers determine how well a structure may tolerate high electric current and adjust processing accordingly to optimize both performance and reliability.
* M.C. Strus, R.R. Keller and N. Barbosa III. Electrical reliability and breakdown mechanisms in single-walled carbon nanotubes. Paper presented at IEEE Nano 2011, Portland, Ore., Aug. 17, 2011.
** M.C. Strus, A.N. Chiaramonti, Y.L. Kim, Y.J. Jung and R.R. Keller. Accelerated reliability testing of highly aligned single-walled carbon nanotube networks subjected to dc electrical stressing. Nanotechnology 22 pp. 265713 (2011).
Laura Ost | EurekAlert!
Linear potentiometer LRW2/3 - Maximum precision with many measuring points
17.05.2017 | WayCon Positionsmesstechnik GmbH
First flat lens for immersion microscope provides alternative to centuries-old technique
17.05.2017 | Harvard John A. Paulson School of Engineering and Applied Sciences
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...
Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...
23.05.2017 | Event News
22.05.2017 | Event News
17.05.2017 | Event News
23.05.2017 | Physics and Astronomy
23.05.2017 | Life Sciences
23.05.2017 | Medical Engineering