Spatially Resolved Transport Properties of Pristine
and Doped Single-Walled Carbon Nanotube Networks
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Abstract
We use noninvasive atomic force microscopy
to probe the spatial
electrical conductivity of isolated junctions of pristine and nitric
acid treated single-walled carbon nanotube networks (SWCNT-N). By
analyzing the local IV curves of SWCNTs and bundles with various diameters,
the resistance per unit length and the contact resistance of their
junctions are estimated to be 3–16 kΩ/μm and 29–532
kΩ, respectively. We find that the contact resistance decreases
with increasing SWCNT or bundle diameter and depends on the contact
morphology, reaching a value of 29 kΩ at a diameter of 10 nm.
A nitric acid treatment moderately dopes SWCNTs and reduces their
average contact resistance by a factor of 3 while the resistance of
the nanotubes remains largely unaltered. Remarkably, the same treatment
on an SWCNT-N shows similar reduction in the sheet resistance by a
factor of 4. These results suggest that the resistance reduction mechanism
is related to the contact modulation with no major impact on conductance
of SWCNTs