Measurements of the transport gap in semiconducting multiwalled carbon nanotubes with varying diameter and length

Individual arc-discharge synthesized multiwalled carbon nanotubes probed with multiple measurement techniques

“…Three-terminal conductance measurements are performed by applying dc voltages (V DS ) from a voltage source (Yokogawa) to the AD-MWNT device electrodes and measuring the current (I) using a low noise current amplifier (Ithaco). 9 The samples were cooled to 4.2 K in a bath cryostat. The current was kept below 1 μA to avoid self-heating and damage to samples.…”

“…In practice, all the samples have a maximum conductance at negative gate voltages. 9 Using the vocabulary of transistor devices, this corresponds to the minimum On-state resistance R MIN of the device. In metallic or quasimetallic samples, though, the conductance variation is almost negligible.…”

“…7,8 AD-MWNTs have been shown to exhibit in their electronic transport properties if the diameter is sufficiently small (<20 nm), a clear division into semiconducting and metallic cases, which is much more obscured in CCVDs. 9 Transmission electron microscope (TEM) images of MWNTs occasionally reveal an abruptly ending single layer within the multishell structure. 10 Especially, if a rupture happens to be in an outer layer, it is visible as a step with the height corresponding to the intershell distance.…”

“…Upon cooling, the transport gap accentuates. In practice, all the samples have a maximum conductance at negative gate voltages 9. Using the vocabulary of transistor devices, this corresponds to the minimum On-state resistance R MIN of the device.…”

On-chip purification via liquid immersion of arc-discharge synthesized multiwalled carbon nanotubes

“…In electronic transport, a low level of defects enables a large mean free path, and thus ballistic transport. Quasiballistic transport has been observed only in the arcdischarge grown MWNTs [2,3], while in CVD-grown tubes conduction has been found to be close to strong localization [4]. Nanomechanical properties have also been directly compared in measurements [5], where the Youngs modulus in CVD-MWNTs was found greatly inferior compared to that of AD-MWNTs.…”