A computer chip using nanotube circuitry can run much faster than a regular silicon chip, for a fraction of the cost, but no one has been able to effectively string together two nanotube transistors, let alone the thousands needed for a chip. Until now: researchers at Stanford University have built the first nanotube circuits, by stamping multiple layers of nanotubes on top of one another.
The stamping method involves using metal electrodes to guide the nanotubes into place. In effect, rather than laying down circuitry one tube at a time, this new technique embeds a mess of nanotubes at once, and then etches away the unwanted tubes. This bulk method saves time, and allows for more complex circuitry.
So far, the Stanford scientists have produced three-dimensional circuits with five to ten nanotubes per micrometer. At that level of complexity, the researchers managed to create a calculator that stores numbers and performs simple operations. A record, to be sure, but no where near the 100-plus nanotubes per micrometer needed to compete with modern silicon chips.
The scientists suspect they can reach that density within 10 years, at which point the carbon nanotube chips will dissipate heat better, run faster, and cost less, than regular silicon chips.