The idea of using molecules as electronic components has been around since at least 1974, when Ari Aviram of IBM in New York and Mark Ratner, then at New York University, showed theoretically that a molecule placed between two metal electrodes can act as a rectifier. However, it took more than 20 years before an individual molecule was successfully connected to two nanofabricated electrodes in an experiment. The difficulties lay in the manipulation of single molecules and in the ability to build electrodes separated by only a few nanometres.
But by the mid-1990s a wonderful new material - the carbon nanotube - had appeared on the scene. Carbon nanotubes are rolled up sheets of graphene just a few nanometres in diameter that can behave as either metals or semiconductors depending on their atomic arrangement. Aided by the mechanical robustness and long length of the nanotubes, many groups around the world quickly succeeded in attaching contacts to these macromolecules.
Since the first report in 1998 of such a carbon-nanotube field effect transistor by Cees Dekker's group at Delft University in the Netherlands impressive progress has been made in improving device performance - in particular during the last couple of months. These efforts have led to the recent report by Phaedon Avouris and co-workers at IBM in New York of a carbon-nanotube FET that can compete with the leading prototype silicon transistors currently available (S Wind et al. 2002 Appl. Phys. Lett. 80 3817).
In the August issue of Physics World, Adrian Bachtold of the Ecole Normale Supérieure, Paris, France, explains the significance of the achievement.