Transport measurements on carbon nanotubes structurally characterized by electron diffraction

A technique for the structural and electronic characterization of the same individual single wall carbon nanotube is presented. Electron diffraction was performed on carbon nanotubes grown across a perforated silicon nitride film and the chiral indices of individual tubes were determined. By means of a scanning-probe-based nanomanipulator a selected tube was then placed in the desired location across prepatterned electrodes. After patterning further electrodes on-top of the tube electronic transport measurements showed room temperature conductances of up to 0.2 $G_0$. The application of a gate voltage allowed the tuning of the room temperature conductance of the device and measurements at liquid helium temperatures showed signatures of a Coulomb blockade, indicating the formation of a carbon nanotube quantum dot.

Figure 1

SEM images showing picking of a SWCNT from the TEM grid with the tungsten STM tips (Ref. 20). The scale bars represent 200 nm.

Figure 2

SEM images showing placing of the carbon nanotube across prepatterned electrodes (Ref. 20). The scale bars represent $1\mu \text{m}$.

Figure 3

Electron diffraction pattern from an individual (17,22) SWCNT and real space image (insert, scale bar represents 5 nm).

Figure 4

Room temperature $I$-$V$ characteristics (inset, measured at $V_g=0$ V) and gate voltage response with $V_{sd}=100\text{mV}$ of the individual (17,22) SWCNT device. $I$-$V$ characteristics remain linear for all applied gate voltages between $-20\mathrm{V}<V_g<20$ V.

Figure 5

$I$-$V$ characteristics (inset, measured at $V_g=0$ V) and gate voltage response of the individual (17,22) SWCNT measured at $4.3$ K. The gate voltage response was measured at zero source drain voltage using standard lock in techniques with an excitation voltage of $400\mu \text{V}$.

Figure 6

Differential conductance as a function of $V_{sd}$ and $V_g$ of the individual (17,22) SWCNT measured at $4.3$ K using standard lock in techniques with an excitation voltage of $50\mu \text{V}$.