The trick to achieving this lies in a second step in which the nanowires growing on the surface are "decorated" with silver nanoparticles by a sputter-coating process. A target, in this case a piece of solid silver, is bombarded with energetic ions, knocking off silver atoms which enter the gas phase and are deposited onto the nanowires. In a final step, the Empa team now grow more nanowires which, thanks to the silver particles, are in electrical contact with the original wires the basis of an electrical circuit on the nanometer scale.
The first step from microelectronics to nanoelectronics
The first electrical conductivity measurements, made with the help of a four-tip scanning tunnel microscope in ultra high vacuum, exceeded the most optimistic expectations the material is of an unusually high quality. "This opens up the possibility of soon being able to manufacture organic semiconductor materials," says Groening confidently. "And that, too, using a simple and economic process." In the meantime the researchers have successfully synthesized increasingly more complex structures of nanowires, and managed to link these together using a good deal of skill and a sure touch.
Take, for example, nanowires consisting of sections made with different starting molecules. If these molecules can transport either only positive or only negative charges, then a diode is created which allows current to flow in one direction alone. Groening speculates that it is quite possible that one day components for nanolectronics and nanophotonics will be made using this technique.
|Contact: Sabine Voser|
Swiss Federal Laboratories for Materials Testing and Research (EMPA)