Carbon Nanotubes
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infinitexh
Feb 26, 2013, 1:45:41 AM2/26/13
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Hey all,
After the recent discussions on more transistor related topics (single electron phenomenons, ballistic transport etc), our recently turned in HW 2 involving graphene/graphite E-k relations and Professor Xiang's hints at including more carbon nanotube materials in the future, I'd like to post a few carbon nanotube related articles that I found very interesting.
Graphene enjoyed a big hype a few years back due to its high mobility, however it was seen with resistance in the transistor application area as it possesses no bandgap (as we seen in class the e-k diagram in the shape of X). Graphene nanoribbon did slightly better, but the creation of a very small bandgap also meant the fundamental reduction of mobility, and therefore also has very little use in the transistor applications.
Carbon nanotubes however, a "rolled-up" version of graphene (that is not however, how actual CNTs are fabricated), are semiconducting or conducting depending on its chirality and provides many practical traits that makes it a potential useful material for future transistor uses. I've attached two papers to this post, one from a recently released IBM paper that details practical upscaling of CNT devices for transistor use fabricated in a production line, providing a possible solution to a major problem that's omnipresent in many nanostructure (dot, wires, tubes, etc) electronics: scaling. The other paper is a general review paper that includes many of the recent and diverse applications Single walled CNTs have seen to be of use in, and extrapolates its potentials in the future, happy reading! =)
IBM Paper
Review Paper
faridazzazy
Feb 27, 2013, 3:18:39 PM2/27/13
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Hi All,
There's a couple interesting things I learned from this review paper that I wanted to point out.
Seeing as how we were just covering ballistic transport in class, single-walled carbon nano-tubes have a large mean free path, so when they are used as a channel material we NEED to consider ballistic transport. The UCB review paper cites sub-10 nm channel length for SWNT FETS which is quite impressive. What's more is that they outperform Si FETS of similar dimension. More can be found here:
The section on artificial skin was quite interesting as well. The pressure sensing element of that device operates by utilizing tunneling current in a TFT array. Applying pressure to the device reduces the tunneling distance of the conductive channels embedded in the rubber thereby increasing current. The full paper can be found here:
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