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Hardware Science Technology

Silicene Discovered: Single-layer Silicon That Could Beat Graphene To Market 67

Posted by Soulskill
from the a-few-months-before-never dept.
MrSeb writes "Numerous research groups around the world are reporting that they have created silicene, a one-atom-thick hexagonal mesh of silicon atoms — the silicon equivalent of graphene. You will have heard a lot about graphene, especially with regard to its truly wondrous electrical properties, but it has one rather major problem: It doesn't have a bandgap, which makes it very hard to integrate into existing semiconductor processes. Silicene, on the other hand, is theorized to have excellent electrical properties, while still being compatible with silicon-based electronics (abstract). For now, silicene has only been observed (with a scanning tunneling electron microscope), but the next step is to grow a silicene film on an insulating substrate so that its properties can be properly investigated."
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Silicene Discovered: Single-layer Silicon That Could Beat Graphene To Market

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  • by sirdude (578412) on Monday April 30, 2012 @02:48PM (#39848333)

    So, Silicene has just been observed for the first time under a scanning tunnel microscope, has had its properties only theoretically proposed, and is hoped to be "as miraculous as Graphene". Nevertheless, the author of the article already believes that it will beat Graphene to the market? Sheesh! Are all headlines nowadays conjured up by a dedicated company full of marketing types?

    • by InvisibleClergy (1430277) on Monday April 30, 2012 @02:54PM (#39848429)

      Remember, "theorized to have" probably means something more like "we got some motherfuckin' mathematical models which say that this shit got all kindsa properties like".

      • Re: (Score:2, Informative)

        by Anonymous Coward

        Remember, "theorized to have" probably means something more like "we got some motherfuckin' mathematical models which say that this shit got all kindsa properties like".

        Is there a version of "theorized to have" without incest and fecal matter? I think I'd be more interested in those models.

    • Re: (Score:2, Insightful)

      by Sarten-X (1102295)

      Are all headlines nowadays conjured up by a dedicated company full of marketing types?

      Of course not. There are several companies in this thriving industry, each taking up a particular niche. There's one for the "everything's racist" stories, some for "mediocrity is amazing", a few for "this is the best/worst/biggest/smallest/oldest/newest thing ever (since that other one)", a couple whose shtick is "everything is interesting to nerds because it will change the world", and so on...

      Guess which website you're on now?

    • by mosb1000 (710161)

      The challenges related to making graphene microelectronics are overwhelming. It may well never come to market. Silicon is great because because it's relatively cheap, and much easier to work with. Plus, all the fabrication techniques we use now work with silicon. So yes, if this technology would work at all it would almost certainly beat graphene to market. It would beat graphene out of the market entirely.

      • by Anonymous Coward

        The challenges with respect to silicen are even worse than for graphen. Silicen does not integrate with Si-electronics in any straight-forward way. Nor does any technology developed for Si-bulk apply to silicen. The handling of silicen is even more difficult than it is for graphen, as the scotch-type method does not work since there is no equivalent for graphit in the silicon world.
        BTW, the material cost of a monolayer of graphen is not so much bigger than the one of silicen. Think of a pencil.

        • The basic technique used in cookie graphene [slashdot.org] is quite cheap, and if you choose to produce it directly on the final substrate the handling should be easy. Dunno what the exact recepie of silicene would be, but sand in a vacuum oven would be my first try.
          The problem with graphene is that carbon doesn't have a band gap, making semiconductors difficult to say the least. Silicon does have a band gap (wich I am using right now, as it is the basis of modern computing.
    • by DCFusor (1763438)
      Maybe, maybe not. Tech exists for photolith, doping and etching and growing oxide, and generally doing you-name-it to silicon that has no counterpart for graphene whatever. It's a pretty big deal, actually. No one's made a graphene integrated circuit AT ALL. Silicon, on the other hand...
    • by jsfs (1329511)
      Well, if it's similar to graphene in ease of making and useful properties, then yes, it could beat graphene to market in actual consumer-type devices because it's easier to integrate into current manufacturing based around silicon. Yes, the headline is optimistic and smells a bit of propaganda, but anything similar to current stuff is more likely to get adopted quickly.
  • "silicon — a material which will probably reach its physical limits in the next 5-10 years" Haven't they been saying that since 1980?
    • by Jeremi (14640) on Monday April 30, 2012 @03:19PM (#39848849) Homepage

      "silicon â" a material which will probably reach its physical limits in the next 5-10 years" Haven't they been saying that since 1980?

      Yes -- and therefore silicon has no physical limits and Moore's Law will continue forever.

    • Re:Physical Limits (Score:5, Interesting)

      by Kjella (173770) on Monday April 30, 2012 @05:32PM (#39850603) Homepage

      "silicon - a material which will probably reach its physical limits in the next 5-10 years" Haven't they been saying that since 1980?

      Yes, there's been a lot of flawed assumptions but now we're nearing the most fundamental limits. The lattice spacing of silicon is about 0.55nm and the process size usually goes down with a factor about 0.6, so:

      22 nm * 0.6 = 14 nm
      14 nm * 0.6 = 8 nm
      8 nm * 0.6 = 5 nm
      5 nm * 0.6 = 3 nm
      3 nm * 0.6 = 1.8 nm
      1.8 nm * 0.6 = 1.08 nm
      1.08 nm * 0.6 = 0.648 nm

      ...and smaller than this just isn't possible. With Intel's tick-tocks there's two years between ticks so 14 years at that rate. But long before that you can start counting the lattices on your fingers, already at 5nm there's only nine left (9*0.55 = ~5) and that's only 6 years away. So late this decade or next decade at the latest Moore's law is dead.

      • Re:Physical Limits (Score:5, Insightful)

        by mhajicek (1582795) on Monday April 30, 2012 @06:07PM (#39851091)

        So late this decade or next decade at the latest Moore's law is dead.

        Unless someone comes up with something clever again.

        • by Kjella (173770)

          Unless someone comes up with something clever again.

          Well, apparently you can turn a single atom [abc.net.au] into a transistor but I don't really see anybody being able to do anything about the size of atoms. Perhaps you can do some other wizardry that'll give us terahertz processors or something but the transistor density won't get denser than this.

      • Yes. And let's not forget that Moore's law is not related to the maximum transistor density achievable at a given time, but to the transistor density achievable at the lowest cost (see Moore's original paper [intel.com], the emphasis on cost is very clear).

        So far every shrink reduced costs too, but the cost reduction may stop before shrinking stops. Smaller processes would then only be used due to higher performance, but would be more expensive. As a practical example, 28nm today is still more expensive than 40nm, an
  • by Sigurd_Fafnersbane (674740) on Monday April 30, 2012 @02:53PM (#39848399)

    I would be a little concerned that the silicon mono-layer would grow a natural oxide very fast and thus consume the silicon?

    The solution in a HEMT transistor is cool in this respect. It is using an un-doped IV-V semiconductor next to a highly doped layer and excess carriers will form a two-dimensional electron gas at the interface. The carriers will move along the surface of the un-doped semi-conducter that since it is un-doped have better mobility and fewer defects than doped material. It must be something along this property they try to re-create with a silicon mono-layer.

  • by ridgecritter (934252) on Monday April 30, 2012 @03:27PM (#39848975)

    "Because of its unique physical properties, graphene, a 2D honeycomb arrangement of carbon atoms, has attracted tremendous attention. Silicene, the graphene equivalent for silicon, could follow this trend, opening new perspectives for applications, especially due to its compatibility with Si-based electronics. Silicene has been theoretically predicted as a buckled honeycomb arrangement of Si atoms and having an electronic dispersion resembling that of relativistic Dirac fermions. Here we provide compelling evidence, from both structural and electronic properties, for the synthesis of epitaxial silicene sheets on a silver (111) substrate, through the combination of scanning tunneling microscopy and angular-resolved photoemission spectroscopy in conjunction with calculations based on density functional theory."

    This is from Phys Rev Letters (DOI: 10.1103/PhysRevLett.108.155501

    they show reasonably convincing LEED (low energy electron diffraction) and STM (scanning tunneling microscope) images of the putative hexagonal close packed array of Si atoms.

    • Re: (Score:2, Informative)

      by Anonymous Coward

      Note that the abstract linked to in the summary (http://prl.aps.org/abstract/PRL/v108/i15/e155501) speaks of "buckled" honeycomb. This is the surface of a Si crystal with diamond stucture. This is NOT the Si-equivalent of graphene, which has a flat or slightly wavy topology. I don't understand why everyone here is speaking of a graphene analogue, when it clearly is not!

  • It makes me wonder if anything will ever replace silicon.

  • You will have heard a lot about graphene, especially with regard to its truly wondrous electrical properties

    In most press releases about graphene I read lately, the focus was on its mechanical properties, and the fact that it is conductive would be merely an (often convenient) side effect.

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