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Scientists Craft Seamless 2D Semiconductor Junctions 49

Posted by Unknown Lamer
from the flat-is-in dept.
vinces99 (2792707) writes Scientists have developed what they believe is the thinnest-possible semiconductor, a new class of nanoscale materials made in sheets only three atoms thick. The University of Washington researchers have demonstrated that two of these single-layer semiconductor materials can be connected in an atomically seamless fashion known as a heterojunction. This result could be the basis for next-generation flexible and transparent computing, better light-emitting diodes, or LEDs, and solar technologies.

"Heterojunctions are fundamental elements of electronic and photonic devices," said senior author Xiaodong Xu, a UW assistant professor of materials science and engineering and of physics. "Our experimental demonstration of such junctions between two-dimensional materials should enable new kinds of transistors, LEDs, nanolasers, and solar cells to be developed for highly integrated electronic and optical circuits within a single atomic plane."
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Scientists Craft Seamless 2D Semiconductor Junctions

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  • That seems to be the pervading problem with nanoscale [X] is that the creation process seems to require an expert with sophisticated instruments manually controlling manipulation tools like lasers to arrange the circuits. It's probably something that could be automated.

    Is there any sort of tech in progress that addresses that problem?

    • There's really not anything out there to handle mass production at this scale, but that's the best part; once you show that it can be done at a small scale, tons of resources come pouring in and generally they figure it out. The chip and solar technology right now is geared for a completely different type of production, so even this technology is amazing, it's got a lot of inertia to fight and would probably be 'born' at a startup, after a lot of failures.
      • Wouldn't semiconductor components on this scale be greatly sensitive to material degradation issues? You don't need much to go wrong for a device like this to stop working.
        • They just need to make it last until the warranty period runs out. Or rather, make the warranty period shorter than the expected failure date.

          Hell, the user flexed it too much anyway.

  • Two dimensional? (Score:2, Informative)

    by jklovanc (1603149)

    If a 2 dimensional sheet has a thickness, in this case 3 atoms, does not that make it a very thin 3 dimensional object?

    • by Anonymous Coward

      Nope. It's common knowledge that 2D fab (which uses little circles as opposed to spherical atoms) is much cheaper than 3D. It just hasn't gained market visibility yet, since almost everything has always used 3D based techniques.

      Though the insurance rates are higher because of what the companies describe as "very sharp edges."

      • Re:Two dimensional? (Score:4, Informative)

        by Dr.Dubious DDQ (11968) on Wednesday August 27, 2014 @03:04PM (#47767911) Homepage
        "Nope. It's common knowledge that 2D fab (which uses little circles as opposed to spherical atoms) is much cheaper than 3D."

        I wouldn't trust anything made on circular-atom technology these days. The only factories that still make the little electron-dots for them are all in dodgy neighborhoods in China, and half the time once delivered they turn out to just be a few photons glued together and painted black...
    • by gstoddart (321705)

      For sufficiently small values of 3 dimensions, it effectively becomes 2 dimensions. ;-)

      So, when you draw a line on paper, it's a line on a plane, even though the ink has some depth to it and the paper has a surface which isn't completely flat under a microscope.

      Or, something like that.

      • by jklovanc (1603149)

        So, when you draw a line on paper, it's a line on a plane,...

        No, it is a representation of a line on a plane using the tools we have. The ink has depth and width so it is only a representation of a one dimensional objects. We live in a 3 dimensional world any solid objects existing in this world has 3 dimensions.

        Can the two dimensional sheet pass through a gap that is 2 atoms wide? No since it is 3 atoms thick and therefore three dimensional.

        • by gstoddart (321705)

          While your pedantry skills are excellent, and your mathematical skills are pretty good ... I think you need to have your humor unit recalibrated, you seem to be a little out of phase.

          I am perfectly aware of the fact that it isn't really a line on a plane in a strict mathematical sense ... heck, I even referenced the thickness of the ink and the fact that the paper has a surface.

          Let me draw you a diagram _________________ ;-)

          Now, what is the depth (stated in microns / femptofortnight) of the above line?

          • by jklovanc (1603149)

            I think you need to have your humor unit recalibrated

            Humor has nothing to do with the incorrect definition of the number of dimensions of an object. I don't see any references to humor in the article.

            Let me draw you a diagram _________________

            That is a two dimensional non-solid object since is has a height, one pixel, and a width, more than one pixel.

            • by gstoddart (321705)

              Humor has nothing to do with the incorrect definition of the number of dimensions of an object.

              Which is why I mentioned your pedantry.

              Let me draw you a diagram _________________

              That is a two dimensional non-solid object since is has a height, one pixel, and a width, more than one pixel.

              In fact, since it's drawn with electrons, it's got depth too. Actually, since it's drawn as pixels on your screen, which by now are probably discrete LED components, it's much more than that.

              It's a signal which causes a seri

              • by jklovanc (1603149)

                When metaphor gets into science then the science becomes inexact. Even if in most cases the material acts like a plane there might be other cases in which it does not act like a plane. If we always treat it like a plane then we assume things will work one way when they might not and we will come to incorrect conclusions.

                Being pedantic is what science is all about. Close enough is not exact.

          • Microns / femptofortnight is a speed. Or, if time is interpreted as a dimension, a dimensionless value like a dozen or a mole.
            2.76E-6 i [goo.gl]

            Of course since it's dimensionless, then that means it isn't a dimension, therefore the line is 2D.

        • by jc42 (318812)

          ... We live in a 3 dimensional world any solid objects existing in this world has 3 dimensions>

          Or, as some physicists like to argue, we actually live in an 11-dimensional space, but in 8 of them, the universe is only one particle or so thick, so we can usually get away with pretending that we're living in a 3-dimensional world.

          (And that's ignoring the time dimension of it all. Lessee; how many of those are there? ;-)

      • by Dcnjoe60 (682885)

        For sufficiently small values of 3 dimensions, it effectively becomes 2 dimensions. ;-)

        So, when you draw a line on paper, it's a line on a plane, even though the ink has some depth to it and the paper has a surface which isn't completely flat under a microscope.

        Or, something like that.

        But what you are drawing is only a representation of a line on a plane, not the actual line on a plane. If all of these 2-dimensional sheets were stacked on top of each other, would they still be 2D? If not, then technically, they aren't 2D to begin with. You would think that scientists would be more accurate with their articulation of complex concepts.

        • by gstoddart (321705) on Wednesday August 27, 2014 @02:37PM (#47767553) Homepage

          You would think that scientists would be more accurate with their articulation of complex concepts.

          Well, apparently they've defined a plane to be 3 atoms thick, and have grossly understimated the collective anal retentiveness of the people reading the article.

          Dude, seriously, it's a dumbed down metaphor written for a press release.

          From the parts of the paper [nature.com] which are available without subscription:

          The junctions, grown by lateral heteroepitaxy using physical vapour transport7, are visible in an optical microscope and show enhanced photoluminescence. Atomically resolved transmission electron microscopy reveals that their structure is an undistorted honeycomb lattice in which substitution of one transition metal by another occurs across the interface.

          I'm quite sure they're not idiots who really think this is a freakin' 2D plane.

          TFA isn't the actual scientific paper, it's the press release intended for the public.

          Now, unclench a little, you're gonna hurt yourself. :-P

          • by MattskEE (925706)

            I'm quite sure they're not idiots who really think this is a freakin' 2D plane.

            Not to be pedantic, but from the same paper abstract but two sentences ahead of what you quoted:

            Creating analogous heterojunctions between different 2D semiconductors would enable band engineering within the 2D plane

            Which shows that they describe the full device including multiple atomic layers as a 2D plane.

            Now the researchers obviously know that this is not a 2D device, in the same way that graphene researchers know that graphe

    • 2D has a special meaning when is comes to materials science. It means something like "as thin as it can possibly be and still be the material".

    • by whit3 (318913)

      It's possible to make a lot of approximations, and some of them depend on the dimensionality.
      Three atoms thick is close enough to two dimensional that a lot of the (quantum mechanical)
      calculations ARE 2-D.
      So, the distinction makes sense (and there's precedent in so-called quantum dot structures)
      to call this two-dimensional.

      Alas, I'm unsure how one would create such a thing
      and keep it intact for a substantial service life with an oxygen atmosphere around.

  • Can someone explain this to me with a car analogy?
    • by gstoddart (321705)

      Can someone explain this to me with a car analogy?

      Imagine your car is exactly as tall as your trailer hitch and your trailer, and once connected it's indistinguishable where your car ends and the trailer begins.

    • Yes. Imagine a Compact Car [wikipedia.org], only much shorter and only three atoms long.
  • Always the same crappy non-journalism. There is not going to be any silver bullets or any miracle-material. Have people learned nothing?

  • Where did they get the 2D atoms from?
  • by Anonymous Coward

    I though HeteroJunction was the only straight bar in the Castro.

  • I am curious as to if a conductor that is only a couple of atoms "thick" can be practical in the real world. Normal conductors can withstand all sorts of abuse as they have a large number of atoms and can afford to have a significant percentage of those atoms moved, removed, converted (reacted with), etc. If you have a conductor that is only three atoms thick, each atom is going to count. How do you prevent just one of those atoms from being dialoged due to mechanical stresses, chemical interaction, cosmic
  • My first thought was 'really fast transistors, and indeed the article preview refers to 'high-speed transistors'. I wonder how fast they are, and how easy it would be to parallell them to gain higher power without sacrificing too much speed; too bad it would cost me $32 to find out... Anyway, this development could lead to faster logic and microprocessors, or even just faster and more efficient switching transistors for power supplies and the like. They might even be good for THz amplification. Any thought

    • "Any thought that this might extend the validity of Moore's Law?"

      No, but now that you ask, it would actually make Moore's law invalid:

      "Moore's law is the observation that, over the history of computing hardware, the number of transistors in a dense integrated circuit doubles approximately every two years."

      Once a transistor is as small as possible, it makes doubling them in the same area rather problematic :-)

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