from Nature
quote:Tiny electrical circuits with a single molecule for each wire have been created in the United States. 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 junction. 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.
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