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Another Step Towards Graphene Semiconductors 33

Posted by samzenpus
from the next-step dept.
derGoldstein writes "Ars has an article up about the two latest 'papers demonstrating that, if you change the way the graphene stacks, you obtain a voltage-controlled bandgap ... Between these two papers, a fairly complete understanding of the bandgap behavior in three-layer graphene has been obtained, leaving only the challenge of making the stuff.'"
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Another Step Towards Graphene Semiconductors

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  • by neokushan (932374) on Monday October 31, 2011 @08:22AM (#37893318)

    Honestly, is there anything Graphene CAN'T do? I'm just waiting for an article to appear that states Graphene may be a cure for Cancer and AIDS rolled into one.
    And then I'm fully expecting another article stating that it's more deadly than asbestos.

    • by Anonymous Coward

      And then I'm fully expecting another article stating that it's more deadly than asbestos.

      I think you'll find that one is nanotubes.

    • by gutnor (872759)
      Graphene is just the new Carbon Nanotube. The new silver bullet to get a grant.
    • Honestly, is there anything Graphene CAN'T do?

      Yes.

      Fortunately we have lasers for those situations.

      • by sjames (1099)

        I'm sure we'll eventually come up with some way to bond graphene to shark skin, then it will be complete.

  • 2 layer vs 3 layer (Score:5, Interesting)

    by vlm (69642) on Monday October 31, 2011 @08:24AM (#37893338)

    I'm having trouble peering thru the journalist filter and not finding any other primary sources.

    To a first approximation, the point seems to be that what we used to be able to do with bi-layer two layer graphene, we can now do with tri-layer three layer graphene. Um, OK, thats nice but not "new".

    http://arxiv.org/PS_cache/arxiv/pdf/1001/1001.5213v1.pdf [arxiv.org]

    So, aside from purely theoretical "thats interesting, just for the sake of physics", what is the point? More durable, better electrical properties, easier to make (thats hard to believe), stronger, easier to customize and control the above, or what? Someone with access to Nature-Physics to read the actual papers could probably respond?

    The article is really poor because it tapdances around the important story which is what I list above.

    • I'm having trouble peering thru the journalist filter and not finding any other primary sources.

      I thought it was fairly clear that this demonstrates the existence of a bandgap that cannot be attributed to substrate effects or contaminants.

    • by gstrickler (920733) on Monday October 31, 2011 @12:28PM (#37896268)

      To a first approximation, the point seems to be that what we used to be able to do with bi-layer two layer graphene, we can now do with tri-layer three layer graphene. Um, OK, thats nice but not "new"

      No, bi-layer graphene can have a band-gap, but it's not controllable, so it can't be used to make a transistor. Conventionally stacked tri-layer graphene has the same problem. What is new is that by changing the way three graphene layers are stacked allows creating a voltage controlled band-gap, which allows for the creation of a transistor.

  • One group observed the photoconductivity of their graphene sheets as a function of wavelength and applied voltage. They showed that the oddly stacked three layer graphene sheets would generate a larger current for particular colors. That is, the light was exciting electrons out of bound states and into conducting states, indicating the presence of a bandgap. Furthermore, this color changed depending on the applied voltage, indicating that the bandgap was changing with the voltage.

    A voltage tunable photod

    • Probably just as usefull as any normal phototransistor out there.

      But this one is a transistor, and made of graphene, a material with very low electrical and thermic resistence.

      • > Probably just as usefull as any normal phototransistor out there.

        Normal phototransistors don't have adjustable bandgaps.

        > ...a material with very low electrical and thermic resistence.

        And thus also potentially much faster than exisitng photodetectors.

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