10.2 Carbon Nanotubes 237
The quantities R 0 and I 0 are fitting parameters. In an ideal case without contact
resistance, R 0 should be equivalent to the resistance quantum. Equation (10.7) has
an interesting consequence: For large values of the voltage, the resistance will get
very large; the electrical conductivity approaches zero. The course of the electrical
resistance, as displayed in Figure 10.10, is described by a voltage-dependent resistance of the single-wall carbon nanotube. The electrical conductance, the inverse
value of the resistance, calculated from the data according to Eq. (10.7) is depicted
in Figure 10.11. This figure makes it clear that a saturation value of the electrical
Figure 10.10 Experimental results obtained on a single-wall carbon nanotube [6]. The
electrical current is plotted against the applied voltage. One sees that the electrical current
approaches a saturation value.
–5
–3
–1
1
3
5
voltage [V]
–25
–15
–5
5
15
25
current [mA]
Figure 10.11 Dependency of the electric
conductivity of a single-walled carbon
nanotube as a function of the applied electric
voltage [6]. In contrast to multiwalled
nanotubes, the conductivity decreases with
increasing applied voltage. With increasing
voltage, the conductivity approaches a
saturation value.
–6
–4
–2
0
2
4
6
voltage [V]
0
10
20
30
conductivity
[MW
–1
]