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IBM Hardware Technology

Graphene Transistors Clocked At 26GHz 174

Posted by CmdrTaco
from the slightly-faster-than-one dept.
KentuckyFC writes "A team at IBM has built the first high quality graphene transistors and clocked them running at 26 GHz . That doesn't quite knock silicon off its perch. The fastest silicon transistors are an order of magnitude faster than that but the record is held by indium phosphide transistors which have topped 1000 GHz. But it's not bad for a new kid on the block. It took silicon 40 years to get this far. By contrast, the first graphene transistor was built only last year. IBM says 'the work represents a significant step towards the realization of graphene-based electronics.' (Abstract)."
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Graphene Transistors Clocked At 26GHz

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  • by circletimessquare (444983) <circletimessquare@NoSpaM.gmail.com> on Thursday December 11, 2008 @11:21AM (#26075161) Homepage Journal

    pencil < pen < sliderule < calculator < computer < supercomputer < pencil

    • Re: (Score:2, Insightful)

      by Anonymous Coward

      +1 Most beautiful use of inequalities

  • This might be a practical limit to the GHz race. There's only so much cicuitry that an electron can go through in that short amount of time. Someone work out the math but in that short amount of time an electron can travel less than a feet(30cm) I'm guesstimating. Sorry got an exam in a couple of hours, don't want to break out the paper and pencil just now.
    • Re: (Score:3, Informative)

      by ttuegel (737533)
      Although there is a practical limit to how far a single electron can go, electrical signals don't consist of a single electron going from one end of the wire to the other. Instead, it's like a game of miniature billiards, with electrons lined up in the wire. You pop one in one end, and another falls out the other end almost instantaneously.
      • Re:Practical limit (Score:4, Informative)

        by blueg3 (192743) on Thursday December 11, 2008 @11:37AM (#26075419)

        There's a practical (and theoretical) limit to how fast this force propagates, too. Fortunately, that's quite high. I don't think electric propagation time is or will be the practical limit on transistor speed.

        • Re: (Score:3, Informative)

          by fizzup (788545)

          The limit on signal transmission speed is relativistic, and about one foot per nanosecond. So the maximum characteristic distance of a chip clocked at 1GHz is about a foot. 10GHz is about an inch. A pentium is about square, and about half an inch on a side. Asynchronous electronics can operate with higher frequency signals, though timing and lead length are still considerations in such devices at really high frequencies.

          • by blueg3 (192743)

            You're right -- we're a little closer to theoretical speed limits, if the signal needs to traverse a substantial fraction of the chip in a single clock cycle.

            One of the newer P4s uses a 146 mm^2 chip, which means it's about 1.2 cm on a side (like you said, about half an inch). Light propagation time across 1.2 cm limits you to 25 GHz in a vacuum -- not sure what the index of refraction in a microchip is.

            • by AuMatar (183847)

              Luckily, transistors and pipeline stages are both much shorter than the length of the chip.

          • by ceoyoyo (59147)

            I seem to recall that EMF in a copper wire propagates at about 40% of c. If a trace in a silicon chip is similar then you have to divide those numbers in half (I'm assuming by "relativistic" you meant "at the speed of light). Plus the relevant length is the length of the trace, which might not be straight.

            That puts the limit on a synchronous pentium-sized chip at about 10 GHz (lower, because your traces aren't all straight lines), which is uncomfortably close to what we do now. Fortunately a sizeable par

            • by lgw (121541)

              Propagation speed is entirely determined by characteristic impedance. For a copper wire, the insulation determines the speed of propagation (but it's about 2/3 c, not 40%). On the old 200-wire cables used by mainframes, the the outer wires were significantly longer than the inner wires (as they were wrapped). Different color wire had different impedances, so the cable was laid with the "faster" colors on the outside to compensate. The guys who could lay a cable by hand (and get it right) were impressive

      • Re: (Score:2, Insightful)

        by Anonymous Coward

        You pop one in one end, and another falls out the other end almost instantaneously.

        The GP is suggesting that at some point that almost becomes very real and very important.

      • Re:Practical limit (Score:4, Informative)

        by Splab (574204) on Thursday December 11, 2008 @11:41AM (#26075495)

        Yes, but unless you can make them break the speed of light there is going to be a very hard limit on how far you can send the signal within an oscillation. At 1 Ghz the signal can travel around 30 centimeters before next cycle, at 5 Ghz you are down to 6 cm (compared to speed of light, since they are going slightly slower mileage will vary), when things go fast enough "almost instantaneously" is quite a long time.

      • Re: (Score:2, Informative)

        by Anonymous Coward

        Because each of these interactions takes time, the signal actually propagates significantly more slowly than the speed of light. The standard rule of thumb is c/2.

      • Re:Practical limit (Score:5, Insightful)

        by mea37 (1201159) on Thursday December 11, 2008 @12:43PM (#26076475)

        You're right that it's not the speed of an electron that matters.

        However, according to relativity, information itself cannot propagate faster than the speed of light. Using your "billiards" analogy, even though the cue ball doesn't have to make it across the table, the 8 ball can't "know" (or in any way react to the fact) that the cue ball started moving any sooner than an object, moving at the speed of light, could cross the table.

        The speed of light is fast, but on the timescales we're discussing it does not translate to "almost instantaneous".

        • Re: (Score:3, Interesting)

          by krenshala (178676)

          However, the position of the sun does get transmitted to the earth faster than the speed of light. Its called aberration, and the instantaneous position of hte sun is 20 arc seconds ahead of the visible (8.3 minute light lagged) position that you see in the sky. Astronomers are unable to point their telescopes in the correct direction if they assume gravity effects travel at the speed of light. they get the correct position if they assume it is instantaneous (at least for stuff in our star system).

          • Re: (Score:3, Insightful)

            by mea37 (1201159)

            I've heard this argued both ways about gravity, and I don't disbelieve what you're saying; but it's a bit off-topic since transistors don't operate on gravity.

          • However, the position of the sun does get transmitted to the earth faster than the speed of light.

            No it doesn't.

            And aberration has absolutely nothing to do with gravity - it's caused by the relative velocity of the earth in the light cone of the sun.

        • So if someone finds a way to transmit information faster than the speed of light, we win?

          Just for revence, please advise:

          What's the expected time for light to travel once around the globe as if it were flat and didn't have to slow down by bouncing off something?

      • by Arterion (941661)

        Force can't travel faster than the speed of light, either.

    • by aperion (1022267)
      My physics professor would use cables to introduce delay in detector signals, 1 foot per nanosecond delay. I always thought that was interesting as it's the same speed as the speed of light...
      • Re: (Score:3, Interesting)

        by clone53421 (1310749)

        it's the same speed as the speed of light...

        Correct... although electrons actually don't propagate that rapidly though a wire, GP was fundamentally correct in that an electron doesn't have to travel the entire length of the wire to transmit the signal. The added electrons at one end of the wire force electrons out the other, and the electrical force is transmitted through the wire at the speed of light. Push an electron into the wire at one end, and you should expect an electron to come out the other end after a delay of wire length/c.

        However, GP inc

    • Re: (Score:1, Interesting)

      by Anonymous Coward

      This might be a practical limit to the GHz race.

      Of course, once we exhaust possible advances in digital technology, the next step is analog computing. There is not even a theoretical limit to that.

  • Duh (Score:1, Interesting)

    by hobbit (5915)

    But it's not bad for a new kid on the block. It took silicon 40 years to get this far. By contrast, the first graphene transistor was built only last year.

    Though mobile phones are not as powerful as mainframe computers, they're not doing badly considering they've only been a relatively short time.

    Therefore it stands to reason that the mobile phones of the future will doubtless be more powerful than the mainframe computers of the future!

    • Is graphene-based circuitry based on silicon the same way mobile phones are based on computers, or are you just throwing a straw man out there for shits and giggles?

    • I know that this is meant as a (not very well thought out) attack on the logic of graphene transistors improving but...
      Your mobile phone of today is actually much more powerful in many respects than a mainframe of the 70's or 80's. The reason that a mainframe of today is still more powerful than a cellphone is because mainframes have been advancing at the same time.
      In addition, your analogy is also a stupid straw man: a graphene transistor is designed to to the exact sa

  • Yes but... (Score:3, Funny)

    by Foske (144771) on Thursday December 11, 2008 @11:26AM (#26075249)

    Running 26 GHz is nice, but... Does it run Linux ?

  • pretty sweet (Score:5, Informative)

    by Goldsmith (561202) on Thursday December 11, 2008 @11:27AM (#26075269)

    IBM and Columbia are working together on this. Their grant calls for them to push this up to 50 THz.

    Oh, and what was done last year was a single electron transistor... normal transistors were available just about as soon as graphene was, in 2004.

    • I'm surprised Slashdot hasn't reported on Prof T P Ma's proposal for Unipolar CMOS, which is structured to rely purely on negative channels, due to the higher electron mobility in comparison to hole mobility. I'm wondering what the electron-to-hole mobility ratio is for graphene?
      • by Goldsmith (561202)

        In pristine, defect free graphene the electron-to-hole mobility ratio appears to be nearly one.

        Finding pristine graphene is a bit difficult, and the hole mobility is generally larger than the electron mobility in "normal" samples (due to contamination from lithography processes and interaction with the silicon oxide usually used as a dielectric).

        The mobility of most graphene devices is around 2000 cm^2/Vs, but with perfect graphene, suspended from the surface and annealed, you can get that up to a maximum o

  • by Anonymous Coward

    Wow. 1000 Ghz... are we getting anywhere near light frequencies now? It would be cool to have transistors able to switch light. Right now laser data transmission has to be converted to electrons, then switched at a much lower frequency. If we could eliminate that step and improve efficiencies... well...this would kick ass!

    • 1000 nm light has a frequency of 3e15 Hz, or 3000 THz. The real thing with optics is to be able to do the processing on light signals instead of electron signals, even in this case the transistors would run at tens to hundreds of GHz. The switching frequency they are talking about here is basically how small they have gotten the internal resistances and capacitances so that the time constant is very very very short. Running one transistor at that kind of speed is one thing, running one hundred million is so
      • by usul294 (1163169)
        Well I'm an idiot, must be too many finals, its 3e14 Hz = 300 THz,for a 1000nm photon, I hope.
    • Not even close. (Score:2, Interesting)

      by frieko (855745)
      You're never going to have clock frequencies in the light range, for the simple fact that light waves are shorter than the diameter of an atom and thus bigger than any transistor.

      Luckily switching light doesn't require transistors that fast. For example, an LCD display switches light directly, without first converting it to electrons. That uses electricity to switch light, but the idea has already been extended to switching light with light in the lab.
      • by drerwk (695572)
        Some photons have a wavelength smaller than the wavelength of an atom. But none of the ones I'm seeing now do.
        Laser red wavelength = 632 nm.
        Helium atomic radius = 31 pm.
    • You wouldn't use a transistor that fast to switch light. It still switches electricity. But what you could do with it is control visible light light we control radio waves right now. Instead of just doing amplitude modulation on a laser carrier wave you could do frequency modulation, phase modulation, all sorts of cool stuff.

      1 THz falls a little short of visible light, but the THz range is actually really interesting. It's a region of the electromagnetic spectrum where it's hard to produce light with RF

  • by Andy Dodd (701) <atd7@@@cornell...edu> on Thursday December 11, 2008 @11:28AM (#26075289) Homepage

    It's a lot harder to get a switching transistor (for digital circuitry) to operate at high speeds than for a transistor to show gain as an RF amplifier.

    26 GHz is incredible for switching circuitry, but it's nothing if you're talking RF signals nowadays. I'm guessing that this was an RF amp given the comments of other transistors being faster in the article summary.

    There is a comment about "clocked at" which implies digital switching, but that could easily be a clueless journalist that has no idea of the difference between transistors in clocked digital circuitry and transistors as RF amplifiers.

    • Re: (Score:3, Informative)

      by zetazentra (1274302)

      I searched for "clock" in the paper on arxiv and got no results! The abstract there is more informative:

      ABSTRACT
      Top-gated graphene transistors operating at high frequencies (GHz) have been fabricated and their characteristics analyzed. The measured intrinsic current gain shows an ideal 1/f frequency dependence, indicating an FET-like behavior for graphene transistors. The cutoff frequency f_T is found to be proportional to the dc transconductance g_m of the device, consistent with the relation f_T=g_m/(2piC_G). The peak f_T increases with a reduced gate length, and f_T as high as 26 GHz is measured for a graphene transistor with a gate length of 150 nm. The work represents a significant step towards the realization of graphene-based electronics for high-frequency applications.

      • by Andy Dodd (701)

        I probably should have read TFA, but your excerpt from it says to me that it is indeed only signal amplification and not switching that was observed at 26 GHz.

      • Re: (Score:2, Informative)

        by ninjackn (1424235)

        A cutoff frequency at 26Ghz means there's nothing to gain! Ba-dump bump!

        *cricket cricket*

        Cut off frequency is defined as the frequency at which the gain (amplification) of the transistor is equal to 1. "Clocking" it at 26GHz would make it about as useful as a wire but a lot more complex and expensive.

        The "important" thing for slashdotters to take away from the abstract is that graphine transistors show similar characteristics to regular FETs and they can be made using things already available in the semicou

  • After reading this Intel engineers are busy restoring Pentium 4 design from backup tapes.
    • Re: (Score:1, Interesting)

      by Icegryphon (715550)
      yeah, where are my 3.8Ghz dual cores? Multicores are nice if you have parallel task, but if you have a serial task.. well.
      • by damburger (981828)
        Non-trivial tasks are almost never forced to be serial. So long as the software industry keeps up, adding cores is fine.
  • It may have taken Silicon 40 years to reach that level, but compare Silicon transistors to the thing it replaced - vacuum tubes - they had totally phased them out within a decade
  • Why? (Score:1, Interesting)

    by docgiggles (1425995)
    At some point, we have to conclude that we are good. Silicon is likely the best material for chips, and will continue to stay that way. other materials have been tried (Germanium was the first) but silicon took precedence because it was cheap and efficient, and I don't see any reason to change that
    • by Foske (144771)

      Graphite is made of carbon, carbon can be made from CO2, CO2 is made by your car. Soon you can refit your exhaust pipe with a miniature chip factory and have Oxigen as only exhaust gas. And you have to ask WHY ?! Wonder what the ratio is between the price of sold chips and the price per gallon of gasoline...

    • Re:Why? (Score:5, Interesting)

      by Fujisawa Sensei (207127) on Thursday December 11, 2008 @12:13PM (#26075945) Journal

      At some point, we have to conclude that we are good. Silicon is likely the best material for chips, and will continue to stay that way. other materials have been tried (Germanium was the first) but silicon took precedence because it was cheap and efficient, and I don't see any reason to change that

      Silicon sucks.

      Pretty much the only redeeming feature it has is that its cheap. when you compare the material properties of Si to GaAs, IIRC, GaAs is better in every way. Unfortunately its also about 100 times as expensive. At least it was back in the mid 90s when I last studied that.

      • by geekoid (135745)

        Just because there are better materials then Silicon, doesn't mean silicon sucks.

      • Re: (Score:3, Informative)

        by Manchot (847225)
        Pretty much the only redeeming feature it has is that its cheap.

        I have two words for you: native oxide. Yes, silicon is cheap, but don't underestimate the value of being able to easily grow silicon dioxide on top of it. I would say that that is the main reason that silicon has completely dominated the industry. Of course, with Intel moving to high-k dielectrics, it may be the case that that could change soon.
      • Unfortunately its also about 100 times as expensive.

        The material or finished good cost?

        I don't care if a CPU is $10 more if it's that much better.

      • GaAs also has an inferior hole mobility, so you're out of luck trying to make anything that requires fast complementary pairs of transistors. Emitter-coupled logic is good to go though - enjoy your CPU eating 400 watts no matter what it's doing.
    • Re: (Score:2, Insightful)

      by evanbd (210358)
      At some point, we have to conclude that we are good. Gasoline is likely the best energy source for cars, and will continue to stay that way. Other sources have been tried (electricity was the first) but gasoline took precedence because it was cheap and efficient, and I don't see any reason to change that.
      • Re:Why? (Score:5, Insightful)

        by canajin56 (660655) on Thursday December 11, 2008 @03:00PM (#26078775)
        At some point, we have to conclude that we are good. Tiger hide is likely the best material for clothing, and will continue to stay that way. Other sources have been tried (leaves were the first) but tiger hide took precedence because it was warmer and less scratchy, and I don't see any reason to change that.
      • by vertinox (846076)

        Other sources have been tried (electricity was the first) but gasoline took precedence because it was cheap and efficient, and I don't see any reason to change that.

        Economic failures aside, there may come another time when gasoline is no longer cheap again.

  • Apparently, the clock that is used to measure the speed of this transistor is even faster. Why not try to make transistors of the same material as the clock? I assume it's some kind of crystal.

    • Re: (Score:3, Insightful)

      by lattyware (934246)
      +1 Dear-God-I-Hope-That's-A-Joke.

      Sarcasm is hard to do online.
    • It's a Swatch with a sweep nano-second hand.
    • by Andy Dodd (701)

      As the article said, this is nowhere near the limit for RF transistors.

      Another person pasted some of the abstract of the actual paper, and despite the article containing the words "clocked at", all that was demonstrated was unity gain (i.e. gain cutoff) at 26 GHz for an RF signal, NOT remotely close to digital switching at 26 GHz.

      RF test equipment that goes to 40-50 GHz is common (albeit expensive), and specialty test equipment even higher.

      See, for example:
      http://www.home.agilent.com/agilent/product.jspx?ni [agilent.com]

  • This is precisely the kind of innovation we need to get to the kind of AI we want. Giving us the ability to do the right-hemisphere's job is what these kinds of transistor speeds will give us.
    • by geekoid (135745)

      Speed has nothing to do with artificial Intelligence. Unless by AI you mean systems that look up 'responses' to mimic what an AI might do.

      Learn the difference.
      AI will come from mimicking the brain. In fact, I will go so far to say that we will have AI before we know everything about the brain.
      Limited testing has shown that a neural network designed to model the brain behave like the brain. Very limited tests at this point.

      • by curmudgeon99 (1040054) <curmudgeon99@noSPam.gmail.com> on Thursday December 11, 2008 @02:48PM (#26078587)

        The brain, we must never forget, consists of two independent hemispheres that work together--via the corpus callosum--but whose functions and methodology are different.

        The left hemisphere, which is bigger and faster and evolved earlier, is mostly discrete storage locations, optimized towards the storage of individual bits of information. This same left hemisphere is optimized toward the processing of linear-sequential pattern-streams of information, such as those found in language and the maintenance of words.

        Current computers work in a manner more similar to the way our older left brain hemisphere works.

        The right hemisphere, which evolved later than the left, is smaller and consists more of axon/dendrite interconnections, making he right hemisphere better optimized towards the processing of visual-simultaneous pattern streams.

        Virtually no current computer system even attempts to model the visual-simultaneous pattern stream processing that is done by the right hemisphere. That consists of taking in patterns of data points and comparing those to known shape and other sub shapes and the associations that are introduced and the recursive processing of gleaning information from images.

        The human ear has about 30,000 neurons leading data to the brain. The human eye has about 1,000,000 neurons leading data to the brain. You can see it's an order-of-magnitude harder problem and so yes, it needs more speed!

    • by Andy Dodd (701)

      1) Demonstrating unity gain (not switching) at 26 GHz is nothing.
      2) AI will likely require an approach similar to actual biological brains - massively parallel at a low clock speed.

  • If IBM can also produce graphene out of greenhouse CO2 they'll also get the thankfulness from the Whole World!
  • by blind biker (1066130) on Thursday December 11, 2008 @12:41PM (#26076431) Journal

    OK, if you are an undergrad deciding on your choice for thesis and postgrad studies, graphene is great. There is a lot of companies, including Nokia, that pour tons and tons of money into graphene research. It's the easiest grant money to get these days.

    That said, there's a reason you don't see much GaAS integrated circuits, even though GaAs has been around for decades, and has much higher carrier mobility (and therefore top speeds) than silicon: it's hard to devise a good IC technology for GaAs. For graphene the problems are way, way bigger than that even. I have seen some attempts of my colleagues (I research in nanosci) at fabricating graphene transistors, and while they can make discrete components with a certain limited rate of success, integration is not even on the horizon. Maybe other people around the world use technologies that are more promising, but it will take a great effort to knock silicon off the top spot for the time being. In fact, I predict a brighter immediate future for Si/Ge and some III/V group compounds as the successors of pure Si, as the next big thing in IC tech.

    • Re: (Score:3, Interesting)

      by chrysrobyn (106763)

      That said, there's a reason you don't see much GaAS integrated circuits, even though GaAs has been around for decades, and has much higher carrier mobility (and therefore top speeds) than silicon: it's hard to devise a good IC technology for GaAs.

      We used to say the same thing about SiGe, but that's starting to make its way into CMOS technologies. Standard 100% bulk Si is hitting the wall of what's possible. Even if geometries are 10-20% bigger, but provide better switching speeds, on currents or lower off

      • Yes, but Graphene seems to be little more than a curiosity at the moment, given just how %*$&ing difficult the stuff is to produce.

        We know how to produce minuscule quantities of the stuff at tremendous expense, but have absolutely no clue how to make it in bulk, as the current process simply doesn't scale, and nobody's been able to devise a better way to do it.

        There's a whole slew of interesting applications for Graphene waiting to be developed if we can figure out how to manufacture the stuff.... and t

  • I tell ya, Graphene-based CPUS will even be able to run Vista at a decent clip.

    -Z

  • The summary mentions graphene transistors "clocked" at 26 GHz. Though the summary author could be using "clocked" to simply mean "measured" (like you clock someone's speed in the 100m dash), it is easy to confuse this with the clocking that occurs normally in digital circuits.

    What is measured at 26 GHz here is the f_T of the transistor, which is a measure of the frequency limit at which point the transistor provides unity gain (or, in other words, past which point the transistor attenuates, rather than
  • Ya, but anything new benefits from that 40 years of experience.

  • ... for the Caffeine based transistor

  • by Chas (5144)

    "But it's not bad for a new kid on the block. It took silicon 40 years to get this far. By contrast, the first graphene transistor was built only last year. "

    Sorry, but this is completely and utterly POINTLESS.

    The state of materials engineering technology now is orders of magnitutde ahead of where it was in the late 60's and early 70's. So why is it such an "achievement" that a new technology, built upon the foundation of an established technology for an older material is so much better than the first gene

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