Nanoelectronics: Do not be afraid of molecular short circuits

Conductivity of two contacting molecules measured

Two C60 molecules in contact (gray). There are electrodes for measuring current (gold) on both sides. Since the molecules measure only a billionth of a meter, extremely high precision of a few billionths of an inch is required to position them in a controlled manner. During the approximation, the scientists examined the flow of current through both moles
Read out

In the future, many electronic components could consist of just a few molecules. Now, for the first time, a Europe-wide collaboration of researchers has designed a circuit of only two molecules and studied its electrical properties. As they report in the journal "Physical Review Letters", such constellations would presumably not be in danger of a molecular short circuit.

Thanks to the constantly progressing miniaturization of electrical components, modern electronics are becoming more and more efficient despite shrinking sizes. But these developments are limited by conventional methods. Because if the tiny structures in the nanometer range are further reduced, there are hurdles that are determined by the special properties of such parts. One of these are unwanted current leaks from touching molecules.

Mini circuit of two fullerenes

Scientists from Germany, France, Spain and Denmark have now for the first time investigated the electrical properties of such mini-circuits of only two molecules. The scientists used soccer-ball-shaped C60 molecules, so-called fullerenes, which are a billionth of a meter in diameter and because of their chemical and physical properties hold great potential for technical applications in materials science and nanotechnology.

First, the scientists lifted one of the molecules with the tip of a scanning tunneling microscope. Then they moved it to a second molecule with a precision of a few billionths of a meter. During the approach, the physicists succeeded in measuring the electric current flow between the two molecules. The understanding of this current, which is strongly dependent on the distance between the molecules, is essential for future molecule-based electronics.

No great danger of molecular short circuits

The investigation shows that the conductivity between the contacting molecules is a hundred times lower than for a single C60 molecule. Therefore, only a weak current flows. This result is extremely important for novel nanoelectronics, where molecules will be packed tightly. Because unwanted short circuits between adjacent circuits could be brought under control with the help of the molecular properties. Additional quantum mechanical calculations are in agreement with the experimental results and also predict a low conductivity between the molecules. display

The newly gained understanding of the electric current flow on the nanometer scale is an important step in the development of molecular electronics. In addition, the extreme precision of the manipulation and control of single molecules demonstrated by the researchers opens up new avenues for the exploration of possible nanoelectronic devices.

(Universit tKiel, 13.11.2009 - NPO)