New research shows that carbon nanotube transistors are twice as efficient as silicon varities


Scientists at the University of Wisconsin-Madison have shown for the first time that transistors fashioned out of carbon nanotubes are actually twice as efficient as regular silicon varieties. This comes after decades of research regarding how carbon nanotubes can be used to design the next generation of computers. Speaking about the breakthrough, recently published in the Science Advances journal, Michael Arnold, a member of the team, said:

Making carbon nanotube transistors that are better than silicon transistors is a big milestone. This achievement has been a dream of nanotechnology for the last 20 years.

Since its discovery back in 1991, these one-atom-thick carbon tubes have been the focus of much scientific research. Its incredibly unique properties, experts believe, could pave the way for more efficient computing devices that at the same time consume significantly less power. Measuring nearly 50,000 times smaller than the width of a single human hair, this wonder material is made up of hexagonally arranged carbon atoms.

Given their miniscule size, millions of these cylindrical tubes can be packed onto wafers similar to the kind found in silicon transistors. In addition to being extremely flexible and stretchable, carbon nanotubes are believed to be over 100 times stronger steel, while weighing only around one-sixth as heavy as the latter. What’s more, the walls of its single layer of atoms actually remain in tact, even when stretched to several hundred microns. The team from NanoScience Instruments added:

 To put this into perspective, if your hair had the same aspect ratio, a single strand would be over 40 meters long.

Like its half-brother grapheme, carbon nanotube is known to be one of the most electrically conductive materials in the entire world. Thanks to the incredibly strong bonds between the carbon atoms, these nanotubes exhibit an interesting phenomenon called electron delocalization, as a result of which electric charges are capable of traveling through the material with zero opposition.

Carbon nanotubes boast nearly 15 times the thermal conductivity of copper, apart from having a current carrying capacity over 1,000 times greater than the latter. Surprisingly, its density never goes beyond half of that of aluminum. These amazing qualities means that carbon nanotubes could soon replace silicon transistors, leading to the development of better, faster and more energy-efficient computers.

According to scientists, using carbon nanotube components in place of silicon parts could potentially enhance the speed of modern computers by five times. Despite its many advantages, carbon nanotubes are not suited for mass production, mainly because they tend to get easily mixed with different types of metallic impurities. Arnold explained:

We’ve identified specific conditions in which you can get rid of nearly all metallic nanotubes, where we have less than 0.01 percent metallic nanotubes.

The technique developed by the team at the UW-Madison involves the use of a special polymer solution to control the properties of carbon nanotubes. This approach, the researchers believe, not only eliminates all impurities, but actually ensures proper spacing between the nano-sized cylinders when placed on a wafer.

As pointed out by the scientists, a 2.5 cm by 2.5 cm transistor made using these carbon nanotubes was found to be twice as efficient as currently-available silicon versions. In their purest forms, however, carbon nanotubes could enhance the performance of a device by nearly five times. At present, the team is trying to get the technique ready for commercial production.

Source: University of Wisconsin-Madison


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