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First Graphene Transistor
An anonymous reader writes "UK researchers are announcing the first ever workable transistor made of graphene — that's one layer of carbon atoms. It's thinner and smaller than a silicon transistor can ever be, and it works at room temperature. When silicon electronics are dead, this is what many speculate is going to take over. There's slight controversy as they decided to announce their results via a review article, rather than wait for their (submitted) peer review paper to come out."
When I was a grad student at UCLA, a postdoc and I collected some data in lab. The professor decided it would well complement the review article to have this new information. So, it happens, and not necessarily to dodge peer review.
The clearance system sounds logical. It is not. It is completely arbitrary. -- John Bolton
You know of a silicon single electron transistor that also works at room temperature? I know some groups have made room-temperature quantum dots previously, but I don't know of any silicon ones. Those other room-temp ones are carbon nanotubes with nano-leads spaced about 10nm apart, in which case they're really graphene already.
Anyway, graphene has a number of very interesting properties, such as its band structure which looks like a Minkowski space-time cone (or MCP from Tron). Graphene is such that its Fermi energy lies exactly at the cone intersection, and is a so-called zero bandgap semiconductor. Density of states around these conical regimes open up all sorts of applications.
Interesting story, one group in physics spent lots of time and $$$ trying to make a nano-pencil to try to create a single graphene layer. Ie, they put a chunk of graphite on an AFM tip, and tapped it onto a substrate, making the world's smallest pencil, and thought they may have had a few areas where the resulting line was single layer thick.
In one of the ultimate cases of getting scooped, a competing team from Harvard took a pencil, scribbled on a piece of paper, and used scotch tape to tap down on the pencil marks. Then tapping that tape onto another substrate gave large areas which had single graphene layers. So the first group was scooped by a team that used literally pennies worth of materials on a process that takes only minutes, while they spent over a year and tens of thousands of dollars on the nano-pencil technique! Cue cliches about thinking outside the box.
make world, not war
The Carbon atom is around 0.2nm width. If they can make gates with a single atom (lets ignore interconnection),
this means that we can go up to 0.2nm (This is just 8 generations away from 45nm or less than 20 years).
I guess that to keep the Moore's law, we'll go to 3D chips much earlier (my 2 cents that we'll have mass
produced 3D chips before or during 22nm).
I'd be curious to see how they deal with electron tunneling, one layer of atoms doesn't sound very stable.
I think "thermal fluctuations" as a reason for the ripples comes about because these interconversions have a high activation energy, so they are likely to occur only at "hot spots" caused that develop from random lattice vibrations. I would imagine that random thermal motion of atoms in the lattice would strain bonds with adjacent carbon atoms, and bond strain could move through the lattice, occasionally adding up to strain a bond enough to break it and form a defect. Just like the pentagons in fullerenes, these defects would provide curvature to the lattice- in the case of a graphene monolayer, evidently just enough to make the sheet "wavy," rather than enough to make it fold in on itself (or rip itself apart trying).
Once again, just a guess- I don't have access to the paper, so I don't know if the nature of the ripples is explained more fully there.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."