Carbon pods are more than a pack of peas

In a step toward a postsilicon age of microelectronics, researchers have found that they can manipulate the electronic character of nanoscopic carbon structures.

CARBON PEA PODS. Illustration shows buckyballs lined up inside a carbon nanotube. In the background are representative electron waves. D. Hornbaker and A. Yazdani, University of Illinois

The researchers worked with hollow, 1-nanometer-wide carbon nanotubes, which they stuffed pea pod style with buckyballs–soccer ball-shape molecules of 60 carbon atoms.

The buckyball-filled nanotubes were first created in 1998 by David E. Luzzi of the University of Pennsylvania in Philadelphia and his colleagues. In the Feb. 1 Science, a team including Luzzi, his colleagues at the University of Pennsylvania, and researchers from the University of Illinois at Urbana–Champaign reports that the molecular peas change the electronic properties of their carbon pods.

The scientists used a scanning tunneling microscope (STM) to image the pea pods structures and to map the motion of electrons in them. They found that the electronic features along each nanotube varied with the positions of the buckyballs.

The researchers also found that they could use the STM to move the buckyballs around inside the tubes, says coauthor Ali Yazdani of the University of Illinois. This manipulation enabled the scientists to confirm that the pods electronic measurements differed when a ball was present and not present at a particular location inside the tube, says Yazdani.

Many scientists are looking to carbon nanotubes and similar nanosize structures as potential successors to silicon. Means to control how electrons move and distribute themselves along nanotubes, which this research could lead to, could hasten that succession, says Yazdani.

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