Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cylinders make circuits spontaneously

30.01.2002


Nanotube grids could make compact computer memories.
© SPL


Carbon nanotubes assemble themselves into electronic grids

Tiny electrical circuits with a single molecule for each wire have been created in the United States1. These grids could replace silicon chips, making computers and memory devices much more compact and powerful than they are today.

The grids comprise carbon nanotubes - long, hollow cylinders of pure carbon a few millionths of a millimetre (nanometres) across and several thousand nanometres long. Depending on how their atoms are arranged, nanotubes act either as metals (like copper wire) or as semiconductors (like silicon).



The grids practically build themselves - just a little encouragement from electrical fields guides them into place. Putting each wire into place individually would be fiddly, time-consuming and expensive.

James Heath, of the University of California, Los Angeles, and colleagues now demonstrate what they predicted four years ago. Namely that if one or both of two wires crossed at right angles are semiconducting, the junction can act like an electronic device such as a diode. And that each device can, in principle, be switched on or off without affecting the others.

This proof of principle raises hopes that a nanotube lattice could form a computer memory, storing one bit of information at each junction2. Being so small, such a circuit could potentially furnish a random-access memory with a storage density around 100,000 times greater than that of a Pentium chip.

Enough rope

Until now, prototype grids had been built from just a few crossed nanotubes, generally by careful manipulation of individual tubes, or by patterning the surface on which they sit. Heath’s team do away with all this.

They disperse the tubes in an organic solvent. Each single-molecule tube sticks to a few others to form a sort of rope. The ropes are 6-20 nanometres thick, up to 20,000 nanometres long, and electrically charged. By applying an electric field across a silicon wafer, the researchers deposit the tubes on the wafer surface, parallel to the field.

Applying another field perpendicular to the first deposits another set of nanotube ropes that cross the first at right angles. The distance between ropes is more or less constant, because electrical charges cause the ropes to repel each other and settle only if far enough from a neighbour. The researchers control this repulsion to adjust the spacing of the grid.


References

  1. Diehl, M. R., Yaliraki, S. N., Beckman, R. A., Barahona, M. & Heath, J. R. Self-assembled, deterministic carbon nanotube wiring networks. Angewandte Chemie International Edition, 41, 353 - 356, (2002)
  2. Rueckes, T.. Carbon nanotube-based nonvolatile random access memory for molecular computing. Science, 289, 94 - 97, (2002).


PHILIP BALL | © Nature News Service

More articles from Power and Electrical Engineering:

nachricht Linear potentiometer LRW2/3 - Maximum precision with many measuring points
17.05.2017 | WayCon Positionsmesstechnik GmbH

nachricht First flat lens for immersion microscope provides alternative to centuries-old technique
17.05.2017 | Harvard John A. Paulson School of Engineering and Applied Sciences

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

Im Focus: Bacteria harness the lotus effect to protect themselves

Biofilms: Researchers find the causes of water-repelling properties

Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

Innovation 4.0: Shaping a humane fourth industrial revolution

17.05.2017 | Event News

 
Latest News

Scientists propose synestia, a new type of planetary object

23.05.2017 | Physics and Astronomy

Zap! Graphene is bad news for bacteria

23.05.2017 | Life Sciences

Medical gamma-ray camera is now palm-sized

23.05.2017 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>