Physicists in the Netherlands have built a transistor based on a carbon nanotube that works at room temperature (S Tans et al. 1998 Nature 393 49). The use of individual molecules as functional electronic devices is one of the holy grails of the electronics industry. The Dutch team, led by Cees Dekker of the Delft University of Technology, were able to switch the nanotube from a conducting to an insulating state by applying a voltage. Last year the Delft team, in collaboration with researchers from Rice University in the US, reported similar behaviour in nanotubes cooled to 5 milliKelvin. Room-temperature operation is a major step towards practical applications.
The biggest challenge in making a single-molecule device is achieving electrical contact between individual molecules. Now new techniques that vaporize carbon to form nanotubes, and deposit material onto silicon oxide substrates, have made it possible to improve the electrical contact. The Delft team made a three-terminal device consisting of the nanotube and two metal electrodes. Electrical measurements on the nanotube shows that it can be described by the semiclassical band-bending models that are used for traditional semiconductor devices. Fabrication of the device – which the team call a single carbon nanotube field-effect transistor or TUBEFET – is described as “relatively straightforward”.
