One Dimensional Transport in Carbon Nanotubes

The devices used in these studies consist of individual single-walled nanotubes (SWNTs) or SWNT ropes[9] to which electrical contacts are made, as shown in Figure 1. The nanotubes are deposited onto 2302 grown on top of a degenerately doped Si wafer. Atomic force microscope (AFM) imaging reveals that the diameters of the deposited objects vary between 1 and 10 nm, with the smallest ones being single SWNTs and the larger ones SWNT ropes. Two methods are used to attach leads to a tube/rope. In the first method[3], a single tube/rope is located relative to prefabricated gold alignment marks using an AFM. Chromium-gold contacts are then deposited on top of the tube/rope using electron beam lithography and lift-off. In the second method[2], electron beam lithography is first used to define leads, and tubes/ropes are subsequently deposited on top of the leads. In addition to the electrical contacts, the degenerately doped silicon substrate can be 1 pm ‘g