back to article Graphene sheaths could boost processor signal speeds by 30 per cent

Scientists at Stanford have found a new use for graphene that will significantly increase the speed of standard computer processors. Most chips use copper interconnects to route signals around their semiconductor circuits, and these are typically insulated with a coating of tantalum nitride. The Stanford team instead used an …

  1. Mark 85 Silver badge

    Contradiction?

    Is this a contradiction...its both a conductor and an insulator? And if it's both, why not eliminate the copper completely? The linked article doesn't explain this... or maybe I'm just too obtuse to understand it.

    1. therebel

      Re: Contradiction?

      That was my thought too, if it's so much better than the copper just ditch the copper.

      1. Jamie Jones Silver badge
        Happy

        Re: Contradiction?

        " That was my thought too, if it's so much better than the copper just ditch the copper."

        I was going to write the same thing!

        Is it maybe that the graphene is an insulator to copper, or to put it another way: you could use graphene for the interconnects, but then you'd need something (say copper) as the insulator! (But even then, why not some non-metal insulator?)

        Baaaah. I'm confused!

        1. Grikath

          Re: Contradiction?

          not a contradiction at all.. electrons will flow much easier within the plane of the graphene sheet than jump from the sheet to the nearest conductor. It wouldn't surprise me if the resistance within the plane of the graphene is actually lower than in the copper main conductor locally..

          It's like the old trick with the tablecloth.. If you pull it away fast enough things on it will stay on the table.. mostly..

          The same "trick" is often used in nature in a host of enzymes, actually.

          1. Mark 85 Silver badge

            Re: Contradiction?

            Thanks for the explanation. So basically, the electrons don't penetrate the grapheme but ride along on the surface next to copper? If voltage were applied to the exterior that were they would ride?

            Given the speeds most processors, etc. run at, I would have expected to see some RF doing the surface ride also on the copper.

            Contradictory or not.. this is fascinating. I hope they can pull this one off and use it commercially.

    2. This post has been deleted by its author

      1. Chemist

        Re: Contradiction?

        "and an insulator"

        AFAIK the nitride layer there as an insulator and to stop the copper migrating into the silicon and affecting its performance - graphene will presumably do the same (and conduct electrons along the sheet"

        1. Grikath

          Re: Contradiction? @ chemist

          It would work that way if you consider the graphene not as a sheet of carbon, but two layers of hydrogen stabilised by a lattice of carbon + electron soup ( extremely simplified, of course).

          To migrate to the silicon any copper atom would have to react with the H of the graphene first.. and there it stops, really. Given the purity of the environment, only direct synthesis would be possible, and while the gods of Quantum could pull a fast one and provide the energy, the local temperature would ensure any CuH formed would revert near-immedeately. ( reverse reaction "happens readily" at 20 K, let alone 20 C...)

          Then there is the issue of inserting into/breaking the benzene-ring lattice itself. And the Si-facing layer of H in the sheet ( with even more ...impressive... energies in play..). Let's just say the odds are stacked against it.

          1. Chemist

            Re: Contradiction? @ chemist

            "It would work that way if you consider the graphene not as a sheet of carbon, but two layers of hydrogen stabilised by a lattice of carbon + electron soup ( extremely simplified, of course)."

            Not sure the point you are making - It's known that a monolayer of graphene is an impermeable barrier under normal conditions ( I have a feeling that protons can tunnel through ) So as I stated copper is not going to be able to diffuse into the silicon

            1. AdamT

              Re: Contradiction? @ chemist

              So this is Graphene Oxide but from Jan '12: http://www.theregister.co.uk/2012/01/27/graphene_blocks_liquids_gases/

              (blocks gases but let's water through)

              1. Chemist

                Re: Contradiction? @ chemist

                "So this is Graphene Oxide ..."

                However graphene oxide != graphene

                In any case the water permeability seems to be along the axis of pairs o sheets

          2. Chemist

            Re: Contradiction? @ chemist

            "f you consider the graphene not as a sheet of carbon, but two layers of hydrogen stabilised by a lattice of carbon + electron soup ( extremely simplified, of course)."

            "To migrate to the silicon any copper atom would have to react with the H of the graphene first.."

            Sorry I should have noticed this sooner but I've been busy today. I'm afraid you are under a misapprehension - graphene doesn't have any hydrogen attached to it - it's pure carbon sp2 hybridized. so planar like benzene but with all bonds carbon-carbon

    3. Lord Raa

      Re: Contradiction?

      I could be mistaken, but I was under the impression that graphite (and by extension, graphene) was an electrical conductor but a heat insulator.

      Whereas diamond was a heat conductor but an electrical insulator.

      Of course, I was "told" that some years ago and have probably misunderstood and misremembered it.

    4. Ship of Fools
      Holmes

      Re: Contradiction?

      ... Why not eliminate the copper completely?

      Perhaps because graphene is one atom thick and has no structural strength? Ergo it needs to be layered on something that does. Why copper? Presumably for practical reasons, for instance because copper is the known quantity and allows an apples-to-apples comparison between graphene and traditional coatings, because common sense says don't change more than one variable at a time if you don't have to, and so on.

      Why assume this is anything other than the usual incremental evolutionary step forward from the current state of the art?

      1. Chemist

        Re: Contradiction?

        "Perhaps because graphene is one atom thick and has no structural strength?"

        Perhaps you'd like to reconsider that rash statement. Just Google it

        1. Ship of Fools
          Facepalm

          Re: Contradiction?

          @chemist : I stand corrected. Strongest material known to man. Yet it seemed so puny on the Sellotape! Icon is for self. Need bigger ship ^^^, etc.

          Moving on, I'm sure you can improve on my answer, if you care to. If the structural strength of graphene is currently realisable (no pun intended), why not ditch the copper entirely and go with a graphene conductor? I don't see any other commentards try to answer that one.

          I suspect my answer was otherwise substantially correct in terms of practicalities, but full disclosure, I'm not really Sherlock, just another random commentard idly speculating

          1. Chemist

            Re: Contradiction?

            "Moving on, I'm sure you can improve on my answer, if you care to. If the structural strength of graphene is currently realisable (no pun intended), why not ditch the copper entirely and go with a graphene conductor?"

            The simple answer is that I don't know

  2. Six_Degrees

    So, graphene pops up quite a bit, with promises of increased strength, or reduced weight, or low friction, or durability, or speed increases in this case.

    Have any of these enhancements actually made it into a real product?

    1. Kevin McMurtrie Silver badge

      Cell phones

      You can buy adhesive "Pyrolytic Graphite" sheets for large sums of money. It's a flexible, lightweight, graphene-like material that conducts heat incredibly well. Cellphones sometimes have a strip of it down the back so the CPU and GPU chips don't burn your hand. Ultra-compact switching power supplies use it to cool components that are spaced closer together than normally possible.

      1. This post has been deleted by its author

  3. g00se
    Coat

    'Graphene sheaths' - the ultimate in prophylactics?

    1. ian 22

      Graphene, is there anything it can't do?

      1. Diogenes Silver badge

        will it blend ?

        1. LaeMing Silver badge
          Happy

          re: Will it blend?

          It will blend all sorts of things that a regular blender blade would choke on!

        2. AbelSoul
          Trollface

          Re: 'Graphene sheaths' - will it blend ?

          Not whilst it's being donned, one would hope...

      2. Robert Helpmann?? Silver badge
        Childcatcher

        Graphene, is there anything it can't do?

        Dunno. Be more than a single atom thick? It's interesting to know all the things it can do, but moreso to know what it does well and in fact better than other materials. In the case of this article, it seems that we have a winner. Next comes scalability and cost on the checklist to determine if it is worthwhile to implement this.

    2. AdamT

      From Nov '13: http://www.theregister.co.uk/2013/11/22/gates_graphene_condom/

  4. Lionel Baden

    Ugghhhh

    Graphene, !!

    Could could could. Please can we get some damn stories on how it is being implemented. This is more frustrating than Sci-Fi.

    Always bloody conjecture for the last few years about graphene. Would absolutely love to see where it has actually made a difference.

  5. Pascal Monett Silver badge

    "needs more work before going into production"

    Right, so I'll file that in the same folder as all those marvelous things batteries are supposed to become some time in some as-of-yet-undetermined future.

    The future will be great - as soon as it gets here. Don't hold your breath.

  6. Andy The Hat Silver badge

    Re Cell phones

    Pyrolytic graphite isn't graphene though it does contain "bits of" graphene as a product of its production process (in the same way that a cabbage contain lignins). The whole point of graphene is that it is a continuous sheet - and the problem with that is there are no interconnects (ie lattice defects) between the sheets to reduce the strength. Pyrolytic graphite is an impure source of graphene which allows lots of intra-lattice bonding - less strong, less electrically conductive but more usable and much, much cheaper than pure graphene.

    Pure graphene is actually really useful for ... err ... and ... ummm ... other that graphene is useful for and obviously other things too. And it's a brilliant material because the His Royal Highness Cameron is investing loads into it and I totally trust his judgement with tax-payers cash.

    1. Roo
      Windows

      Re: Re Cell phones

      "And it's a brilliant material because the His Royal Highness Cameron is investing loads into it and I totally trust his judgement with tax-payers cash."

      In the interests of calibrating my sarcasm detector...

      Would that be the same David Cameron who decided that drug policies should not be guided by evidence gathered from scientific studies because he personally disagreed with the conclusions ?

  7. Conundrum1885 Bronze badge

    Sort of like

    The myelin sheath around an axon?

    This is intriguing, presumably the graphene can't just be deposited as clusters of atoms on say sapphire and then mechanically attached to the completed silicon wafer to get the speed advantage without having to deposit graphene directly?

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