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Self-Aligning Wires for Nanoelectronics

Miniaturization in microelectronics is beginning to reach its physical limits, say researchers at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) Institute of Ion Beam Physics and Materials Research, who are seeking new methods for device fabrication. They have discovered that one method may be the DNA origami technique in which individual strands of the biomolecule self-assemble into arbitrarily shaped nanostructures.

However, they caution that the formation of entire circuits requires the controlled positioning of these DNA structures on a surface, which had previously only been possible using very elaborate techniques.

The HZDR researchers use a simpler strategy combining DNA origami with self-organized pattern formation. In the DNA origami technique, DNA structures self-assemble as long strands of the biomolecule fold into complex, predefined nanoscale shapes by pairing with multiple smaller DNA strands. Their method used the technique to produce small tubes with lengths of 412 nanometers and diameters of six nanometers. These structures can be used as scaffolds for manufacturing nanoelectronic components like nanowires.

In order to align these nanotubes on the surface, the researchers irradiated the surface onto which they wanted to place the nanostructures—in this case, silicon wafers—with ions, which resulted in the spontaneous appearance of ordered nanopatterns resembling miniature sand dunes.

Through electrostatic interactions between the charged DNA nanostructures and the charged surface, the nanotubes align themselves in the valleys of the “dunes”. This technique works so well that not only do the small tubes follow the wavy patterns, they even replicate occasional pattern defects, which should allow for production of curved nanocomponents, they explain.

The new technique is quick, inexpensive, and simple. Since aligning the small tubes is based exclusively on electrostatic interaction with the prestructured surface, using this particular method the nanotubes could also be arranged into more complex arrays such as electronic circuits. They say that the structures can be attached to individual transistors, for instance, and connected them electrically. This way, DNA-based nanocomponents could be integrated into technological devices and contribute to further miniaturization.

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