Quantum conductance in single- and double-wall carbon nanotube networks

Abstract

The electrical conductance of single- and double-wall carbon nanotube systems was measured by a mechanically controllable break-junction technique using freestanding nanotubes not subject to any chemical modification. For metallic single-wall carbon nanotubes, two channels with transmission coefficient of 0.88 contribute to ballistic electronic transport at room temperature. In double-wall carbon nanotubes, one metallic channel contributes to ballistic electronic transport and additional field- and temperature-dependent two-channel contributions were observed.

Quantum conductance in double-wall carbon nanotubes grown by chemical vapor deposition

“…18 The work of Poncharal et al 4 reported values of 0.6G 0 and 0.8G 0 as the most frequently observed noninteger values of the conductance from protruding bundles. Recently, we have observed similar results in pristine, freestanding SWNT and DWNT systems at room temperature, 8 and concluded that SWNTs are two-channel ballistic conductors with a transmission coefficient of 0.88. We have also suggested these DWNTs, produced by the coalescence method, are approximately one-channel ballistic conductors with additional field-and temperature-dependent twochannel contributions.…”

“…The aim is to elucidate interwall interaction effects on the transport properties in DWNTs. The dispersion in diameter and interwall separations for this CVD-grown DWNT sample is superior to that of DWNTs produced by the C 60 -SWNT coalescence method 14 used in our previous study 8 and is therefore closer to the ideal of a completely phase-pure DWNT sample.…”

“…1, 2 The landmark paper of Frank et al 3 provided evidence for ballistic conduction in pristine freely suspended multiwall carbon nanotubes ͑MWNT͒. Subsequent research has confirmed ballistic transport in MWNT bundles at room temperature [4][5][6][7][8] and that the ballistic conduction in nanotubes is the result of a high degree of structural integrity and a low level of inelastic scattering. The ballistic conductance regime is governed by the Landauer-Büttiker equation 9…”

“…8 No chemical modification, other than exposure to the atmosphere, or exposure to harsh chemical environments is required for sample preparation hence there is a high degree of confidence that the measurement probes the intrinsic electronic structure.…”

“…We have also suggested these DWNTs, produced by the coalescence method, are approximately one-channel ballistic conductors with additional field-and temperature-dependent twochannel contributions. 8 Interpretation of the coalescenceproduced DWNT conductance data was limited by the large dispersion in inner-and outer-wall diameter and interlayer separation.…”