This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: Electrical and thermal transport in metallic single-wall carbon nanotubes on insulating substrates Eric Pop a ! Laboratory for Advanced Materials and Department of Chemistry, Stanford University, Stanford, California 94305 and Thermal Sciences Department, Mechanical Engineering, Stanford University, Stanford, California 94305 David A. Mann Laboratory for Advanced Materials and Department of Chemistry, Stanford University, Stanford, California 94305 Kenneth E. Goodson Thermal Sciences Department, Mechanical Engineering, Stanford University, Stanford, California 94305 Hongjie Dai b ! Laboratory for Advanced Materials and Department of Chemistry, Stanford University, Stanford, California 94305 s Received 1 September 2006; accepted 12 February 2007; published online 11 May 2007 d We analyze transport in metallic single-wall carbon nanotubes s SWCNTs d on insulating substrates over the bias range up to electrical breakdown in air. To account for Joule self-heating, a temperature-dependent Landauer model for electrical transport is coupled with the heat conduction equation along the nanotube. The electrical breakdown voltage of SWCNTs in air is found to scale linearly with their length, approximately as 5 V/ m m; we use this to deduce a thermal conductance between SWCNT and substrate g < 0.17±0.03 W K-1 m-1 per tube length, which appears limited by the SWCNT-substrate interface rather than the thermal properties of the substrate itself. We examine the phonon scattering mechanisms that limit electron transport, and find the strong temperature dependence of the optical phonon absorption rate to have a remarkable influence on the electrical resistance of micron-length nanotubes. Further analysis reveals that unlike in typical metals, electrons are responsible for less than 15% of the total thermal conductivity of metallic nanotubes around room temperature, and this contribution decreases at high bias or higher temperatures. For interconnect applications of metallic SWCNTs, significant self-heating may be avoided if power densities are limited below 5 m W/ m m, or if the SWCNT-surrounding thermal interface is optimized. © 2007 American Institute of Physics . f DOI: 10.1063/1.2717855 g I. INTRODUCTION Single-wall carbon nanotubes s SWCNTs d are cylinders formed by a sheet of hexagonally arranged carbon atoms s graphene d wrapped into a nanometer-diameter tube. 1 , 2 These molecular wires have attracted considerable scientific and engineering interest due to their outstanding electrical and thermal transport properties. Depending on their wrapping s chiral d angle, SWCNTs exhibit either semiconducting or metallic behavior. 3 Within integrated circuits, semiconduct- ing SWCNTs can be used for transistor device applications, 4 while metallic SWCNTs have been proposed as advanced interconnects....
View Full Document