Researchers at the National Institute of Standards and Technology (NIST) have found device reliability problems when using carbon nanotubes.

They found that while carbon nanotubes used as interconnects between metal electrodes.can sustain extremely high current densities (tens to hundreds of times larger than that in a typical semiconductor circuit) for several hours, they slowly degrade under constant current.

Of greater concern: the metal electrodes failed: the edges receded and clumped when currents rose above a certain threshold. The circuits failed in about 40 hours.

They also 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.

Despite the reliability concerns, the researchers envision 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,” says Mark Strus, a NIST postdoctoral researcher.

Ref.: 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

Ref.: M.C. Strus, et al., Accelerated reliability testing of highly aligned single-walled carbon nanotube networks subjected to dc electrical stressing, Nanotechnology 22 pp. 265713 (2011); [DOI: 10.1088/0957-4484/22/26/265713]