Graphene Transistors 10x Faster Than Silicon

Asadullah Ahmad writes "IBM has created transistors made from carbon atoms, which operate at 100 gigahertz, while using a manufacturing process that is compatible with current semiconductor fabrication. With silicon close to its physical limits, graphene seems like a viable replacement until quantum computing gets to desktop. Quoting: 'Researchers have previously made graphene transistors using laborious mechanical methods, for example by flaking off sheets of graphene from graphite; the fastest transistors made this way have reached speeds of up to 26 gigahertz. Transistors made using similar methods have not equaled these speeds.'" The other day we discussed what sounds like similar research by a group of scientists at Tohoku University; that team did not produce transistors, however.

Comments

Didn't Produce Transistors? Oh Come On!

[eldavojohn]

The other day we discussed what sounds like similar research by a group of scientists at Tohoku University; that team did not produce transistors, however.

Surely that is some sort of joke. From the summary of the Tokyo University article:

A new paper entitled Epitaxial Graphene on Silicon toward Graphene-Silicon Fusion Electronics published by a group of physicists at Tohoku University in Japan has demonstrated that they can grow graphene on a silicon substrate and pair that technique with conventional lithography to create a graphene-on-silicon field effect transistor.

Not to mention that article is a myriad of highly moderated comments admonishing the staleness of graphene on silicon transistors.

Re:Didn't Produce Transistors? Oh Come On!

[John Hasler]

Note that the Tohoku group grew graphene on silicon while IBM produced graphene transistors on silicon carbide. These are complementary efforts, not competing ones.

Re:Didn't Produce Transistors? Oh Come On!

[DJRumpy]

But there is a limit, no mistake about it. Look at modems. They went through this same limit/new limit methodology for years before they were replaced outright. I think this definitely puts silicon in it's death throws, but I expect some last minute breakthroughs that will push it a bit farther than previously though possible. This is a good thing, in that it forces us to optimize current technologies in ways that we didn't previously consider (like compression did for modems) that in turn was applied to all sorts of communication technologies, and arguably to other technologies outside of communications.

I just see this as a necessary step before pushing off into the next big thing.

Re:Didn't Produce Transistors? Oh Come On!

[wurp]

I think you're just too young to have seen the whole chain of "limits" on modem speeds. For a long time we were told that 9600 baud was the absolute maximum speed, limited by the fundamental physics of modem technology over phone wire.

See http://en.wikipedia.org/wiki/Modem#Breaking_the_9.6k_barrier

Re:Didn't Produce Transistors? Oh Come On!

[wurp]

Again, that's very easy to say in retrospect. I believe this is an almost identical situation: we have a very complex set of interactions from which we derive one number: "transistor switch speed". We believe we understand those relations well enough that we can derive a fastest speed any possible silicon design can give.

This speed is far more similar to the "maximum" modem speed than it is to the melting point of some substance.

Before Ungerboeck's work, information theory seemed very clear about the fastest possible rate at which data could be reliably sent on the frequencies that would "stay on the wire" without bandwidth bleedover. Ungerboeck just demonstrated that there were artificial assumptions underlying the information coding theory on which that speed was based.

You're looking at documentation after-the-fact on modem speeds, which rightly enough talks about revolutions in theory. From the point of view of people before the revolution in the theory, you talk about physical limits. All limits we calculate are by definition theoretical limits, though.

To paraphrase Arthur C. Clarke: When a scientist or engineer states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.

Re:Didn't Produce Transistors? Oh Come On!

[robathome]

I think you're just misunderstanding the problem.

The "baud rate" of telephone lines is pretty slow. Baud rate is the number of symbol transitions per second the media can support. Baud rate and bits/second have not been equivalent since Bell103a/V.21 frequency-shift-keyed modems, where 300 baud meant 300 bps, each state transition being a discrete tone that indicated a "mark" or "space" (0/1). From then on, Bell 212a/V.22 used phase-shift keying to get 1200 bps out of a 600 BAUD symbol rate, encoding two bits of information per symbol.

POTS lines are pretty pokey - the practical maximum BAUD rate is less than 3500 symbols/sec. Where speed advancements were made in later evolutions of POTS modems were in the number of bits that could be encoded per symbol, using QAM and Trellis Modulation. A 33.6 kbps modem is encoding 10 bits per symbol onto a 3429 baud carrier.

So, when you kept hearing "phone lines max out at less than 4800 baud", that was correct. The engineers kept wringing higher bit rates out of narrow-band POTS by putting more information on each of the symbols transmitted.

Then, with V.70 and V.90, the modulation schemes took advantage of certain characteristics of non-muxed POTS lines to use PCM digital encoding instead of an analog audio carrier. Unfortunately, if you were serviced through a SLC-96 ("Slick") muxed subscriber loop, which multiplexed the signal from your subscriber line to the central office, you could only connect with older analog modulation schemes such as v.32/v.32bis/v.34.

Commercially Viable

[LikwidCirkel]

With all the stories of highly-experimental new, novel types of transistors - the majority of which are expensive-research only with no chance of commercialization any time soon, it's refreshing to see something that actually takes production feasibility into account.

My prediction

[Thanshin]

Year 2173:

"Hidrogen-Unobtanium polycomposites seems like a viable replacement until quantum computing gets to desktop."

Just remember.

[AltGrendel]

The first patent for transistors was filed in 1925.
Look where they are now.

3D chips

[BlueParrot]

To be honest I'm more interested in seeing proper 3D chips become reality. If you find some affordable way to produce chips with, say 10 000 layers, then processing power per volume unit would increase rapidly.

I think the major obstacle is going to be what to do about heat. The center of such a chip-stack would probably get quite hot so you probably want to run some form of liquid cooling through the chip itself. Alternatively materials like silicon carbide or diamond might be able to cope better with the high power density.

hold yer horses

[lurgyman]

Before you get yourselves worked up, realize there is no mention in this article or the original article in "Science" for applying this for computing. There's somewhat of a misstatement in the technology review article - if you look at the actual article in Science (http://www.sciencemag.org/cgi/content/abstract/327/5966/662), the 100GHz figure is the unity (or cutoff) gain frequency (e.g., how high of a frequency you can build an amplifier) and not switching. There is no mention of switching in the paper by the IBM scientists, and that is the application relevant to computing. Even TFA's expert is talking about using this in analog communication frontends, folks. Sorry.

Re:9x faster, not 10x faster

[Just Some Guy]

These transistors are only about 9x faster than silicon, not 10x faster as the Slashdot headline claims.

Oh, well, in that case don't even bother.