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Graphene Transistors 10x Faster Than Silicon

Posted by kdawson on from the can't-be-too-rich-either dept.

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.

22 of 170 comments (clear)

  1. Didn't Produce Transistors? Oh Come On! by eldavojohn · · Score: 4, Informative

    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.

    --
    My work here is dung.
    1. Re:Didn't Produce Transistors? Oh Come On! by John+Hasler · · Score: 4, Informative

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

      --
      Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
    2. Re:Didn't Produce Transistors? Oh Come On! by DJRumpy · · Score: 4, Insightful

      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.

    3. Re:Didn't Produce Transistors? Oh Come On! by wurp · · Score: 4, Informative

      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

    4. Re:Didn't Produce Transistors? Oh Come On! by wurp · · Score: 4, Insightful

      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.

    5. Re:Didn't Produce Transistors? Oh Come On! by robathome · · Score: 5, Informative

      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.

      --

      At 3 A.M. you can see people's auras; at five you can see their contrails...
    6. Re:Didn't Produce Transistors? Oh Come On! by phantomfive · · Score: 3, Insightful

      Wow, way to close your eyes to new knowledge and ideas. That guy had something extremely insightful to say, and you missed it for the sake of an argument (and what a waste of an argument! That processor speed was a stupid thing to chase? Did you never use a Commodore 64? Sigh).

      --
      Qxe4
  2. Commercially Viable by LikwidCirkel · · Score: 5, Insightful

    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.

  3. My prediction by Thanshin · · Score: 5, Funny

    Year 2173:

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

    1. Re:My prediction by ground.zero.612 · · Score: 3, Funny

      Year 2173:

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

      I came here from the year 2242 to tell you that you're wrong.

      --
      "Be prepared, son. That's my motto. Be prepared." --Joe Hallenbeck
  4. How long until you can buy it? by Cytotoxic · · Score: 3, Funny
    IBM research is typically the traditional 10 years away - but not this one... from TFA:

    "This is not pie-in-the-sky stuff, this is real," he says. "This development is really going to turn into a communications device not too long from now."

    So, I won't be playing Crysis on this transistor next month, but I might be using it to make a phone call "not too long from now".

    1. Re:How long until you can buy it? by chrysrobyn · · Score: 3, Interesting

      IBM research is typically the traditional 10 years away - but not this one

      My VLSI professor was in the forefront of the industry. He had some very good contract with some good R&D firms. One day, he told us that copper might one day replace aluminum as wires in chips. The lower resistance would make a big difference, but nobody had overcome the increased reactance yet. The next day, IBM announced that they had figured it all out. A year later, copper interconnect was being used in chips, and 6 months later, in iBooks. The same professor in a subsequent class was discussing SOI with similar promises of improvements, and similar "nobody has it figured out yet". A few weeks later, IBM came through again with an announcement. 2 years later, there it was in products.

      With game changers like SOI and copper, IBM has gone to market in much less than 5 years.

      As a former circuit designer, and still a CPU engineer, I can say without hesitation that I don't care about graphene. The transistors aren't the big factor anymore. Sure, smaller transistors are good to increase transistors per die, and reduce the distance between them, but wire RC delay is the big deal. Even if the Ioff goes down and Ion goes up, the speed of the chip isn't going to change much.

      Things aren't going to get much better than copper -- it's very good already. Even if they upgraded to slightly lower resistance silver (and talk about a reactive metal!), the delay wouldn't change much. Lower K dielectric would help too. There are some minor improvements that can be done, but we're probably talking 5% here and there, and they probably don't add up to 20%.

      Architecture changes are going to be important, from instruction optimization to multiple cores. The automated synthesis tools available also have an amazing amount of potential improvement -- placement and routing is a field with a lot of graph theory headroom. There is a world of difference still between "good enough" synthesis and what can be done by a well trained technician.

  5. Just remember. by AltGrendel · · Score: 4, Informative

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

    --
    The simple truth is that interstellar distances will not fit into the human imagination

    - Douglas Adams

  6. 3D chips by BlueParrot · · Score: 4, Interesting

    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.

  7. Sounds cheap by marciot · · Score: 3, Funny

    It was bad enough when computers were made out of mere sand, now they will be made out of coal?

    Can't they make computers out of sapphires or something so I can feel sophisticated when I buy it?

  8. Bad / Incorrect Article by Anonymous Coward · · Score: 3, Insightful

    "The prototype devices, made from atom-thick sheets of carbon, operate at 100 gigahertz"

    Define operate? This sounds like the cut-off frequency, which is 100s of GHz for Si CMOS. How is 200GHz 100GHz? And no, this does not mean it can switch this fast. If it can switch this fast, it would likely operate into the THz, and we would be interested in using it for THz applications. Maybe operate is maximum stable oscillation frequency? Ft? Fmax? It's sure as hell not a switching frequency, despite what the article tells us.

    "Growing transistors on a wafer not only leads to better performance, it's also more commercially feasible"

    Growing transistors on a wafer? As compared to what? A waffle?

    Done reading... moving on...

  9. Interconnects by John+Hasler · · Score: 3, Interesting

    Graphene will probably be at least as important as a replacement for metallic interconnects as for transistors. Much of the area of a chip is covered by interconnects they are responsible for much of the heat and delay.

    --
    Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
  10. silicon on sapphire by confused+one · · Score: 3, Insightful

    http://en.wikipedia.org/wiki/Silicon_on_sapphire

  11. 9x faster, not 10x faster by noidentity · · Score: 3, Informative

    The prototype devices [...] can switch on and off [...] about 10 times as fast as the speediest silicon transistors.

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

    1. Re:9x faster, not 10x faster by Just+Some+Guy · · Score: 5, Funny

      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.

      --
      Dewey, what part of this looks like authorities should be involved?
  12. Re:Military Application? by derGoldstein · · Score: 3, Funny

    You're assuming that the transistors themselves will have to go into a hostile environment. Some of them do, but when you're talking about HPC then they'll probably be in a remote location, safe and protected (like Cheyenne Mountain, maybe near the Stargate...).

    --
    Entomologically speaking, the spider is not a bug, it's a feature.
  13. hold yer horses by lurgyman · · Score: 5, Informative

    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.