Carbon nanotubes have been touted as an answer to an array of medical device–related applications, from drug delivery in cancer treatments to batteries. However, despite such advantages as their presumed ability to carry 1000 times more electric current than a metal conductor of the same size, scientists at the National Institute of Standards and Technology (NIST; Gaithersburg, MD) are questioning nanotubes' reliability.
|Micrograph of recession and clumping in gold electrodes after the application of 1.7 V of electricity has been applied to carbon nanotube wiring for one hour. (Image by M. Strus)|
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. Their results show that although nanotubes can sustain extremely high current densities tens to hundreds of times larger than that in a typical semiconductor circuit for several hours, they degrade slowly under constant current. Of greater concern to the scientists is that the metal electrodes fail when currents rise above a certain threshold. Failure occurs within about 40 hours.
What's different about the NIST researchers' work is that they are studying how carbon nanotubes may function in real electronic devices over the long term. To support industrial applications, the NIST team is developing measurement and test techniques and studying a variety of nanotube structures to determine what happens when nanotubes and metals intersect and when nanotubes interact with other nanotubes.
For more information on research into the reliability issues associated with carbon nanotubes, see the NIST article.