Conduction

Also, because each nanotube is so small, they all exhibit strange quantum phenomena [1]. For example, because each tube is so small, and because of the strong electrostatic forces acting around the edge of each nanotube, only one electron can fit through any point in the tube at any one time (n.b. this is similar to red blood cells squeezing through capillaries):

This causes a “blockade effect” [4], meaning nanotubes do not obey Ohm's law all the time.

As one electron is pushed through the nanotube (by a small voltage), there will be a small current. But, if the voltage is increased further, the current will remain the same, until there is a high enough voltage to force a second electron through, and so on:

This blockade effect means nanotubes can conduct high currents, and handle high current densities (e.g. >1 MA per cm²), without deteriorating [5], as the electrons are forced to be so close together. This means that computer chips constructed of nanotubes can be easily made faster [3], as well as smaller.

This also means electrons are forced to travel down the centre of the nanotubes and not around the carbon atoms, unlike metals, where electrons move amongst the metal ions and lose energy:

This means nanotubes have a much lower resistance than equivalent nano-sized copper. This means that miniturisation of computer chips does not bring with it the problems of ultra-high resistances, like with copper.

The only problem with this seemingly ‘perfect' conductor is that it is very difficult to connect to other components. As other nanotubes cannot be used to connect existing nanotubes to other components, a low resistance gold-solder must be used [6,10]. It is also very difficult to experimentally measure the resistance of nanotubes as the resistance of the measuring device is likely to be very similar to, if not larger than the nanotube itself.

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