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The basic premise of "constructive destruction" is that in order to construct a dense-array of semiconducting nanotubes, the metallic nanotubes must be destroyed. This is accomplished with an electric shockwave that destroys the metallic nanotubes, leaving only the semiconducting nanotubes needed to build transistors. Here is how it works:
The scientists deposit ropes of "stuck together" metallic and semiconducting nanotubes on a silicon-oxide wafer.
A lithographic mask is projected onto the wafer to form electrodes (metal pads) over the nanotubes. These electrodes act as a switch to turn the semiconducting nanotubes on and off.
Using the silicon wafer itself as an electrode, the scientists "switch-off" the semiconducting nanotubes, which essentially block any current from traveling through them.
The metal nanotubes are left unprotected and an appropriate voltage is applied to the wafer, destroying only the metallic nanotubes, since the semiconducting nanotubes are now insulated.
The result is a dense array of unharmed, working semiconducting nanotube transistors that can be used to build logic circuits like those found in computer chips.
Moore's Law says that the number of transistors that can be packed on a chip
doubles every 18 months, but many scientists expect that within 10-20 years,
silicon will reach its physical limits, halting the ability to pack more
transistors on a chip. Transistors are a key building block of electronic
systems -- they act as bridges that carry data from one place to another inside
computer chips. The more transistors on a chip, the faster the processing speed.
This advance by IBM scientists could have a profound impact on the future of
chip performance. |
