2.3.4 Carbon Nanotube FET

Carbon nanotubes are cylindrical sheets of one ore more concentric layers of carbon atoms. Experiments have shown that the tubes can either have metallic or semiconducting properties. Their band structure depends on the position of the carbon atoms forming the tube. Particularly single-wall carbon nanotubes show superior electrical properties and are considered promising candidates for future nanoelectronic applications, either as interconnects or active devices. Semiconducting nanotubes can be used as active elements in field-effect transistor (FET) designs. Two possible applications of carbon nanotubes as transistor devices are shown in Fig. 2.10 [36,37]. Single-wall carbon nanotubes are ballistic conductors, so the current is governed by LANDAUER's equation. This, however, implies that the minimum resistance of a metallic nanotube is $h/4\ensuremath {\mathrm{q}}^2 \approx 6.5$k$\Omega$. It is now generally accepted that the transport in the tubes is dominated by SCHOTTKY barriers at the metal contacts [38].

Figure 2.10: A lateral (left) and an axial (right) carbon nanotube FET.

A. Gehring: Simulation of Tunneling in Semiconductor Devices