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Can use Carbon to create Diode

  1. Jul 6, 2012 #1
    Can use Carbon to create Diode instead of
    Silicon-germanium ?
    if yes why we don't have carbon diode? what is advantages and disadvantages?
  2. jcsd
  3. Jul 6, 2012 #2


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    Since we need single crystal material, we're talking diamond. Historically, growing large single crystal diamonds has not been possible. If I could grow large, high-quality diamonds, I would probably focus on selling them as gems first before I would sell them to make electronics. Also, finding a good n-type dopant in diamond has been a problem (boron works well for p-type diamond, but for reasons I don't understand, the historic n-type dopants like phosphorous don't work well in diamond). However, there is a large research effort going on to make diamond electronics, and many people believe it will eventually replace silicon due to its higher thermal and electrical conductivity. Here's one recent article:

  4. Jul 6, 2012 #3
    I think that in the past carbon in the form of coke was one of the things used as the diode detector for crystal set radios.
  5. Jul 6, 2012 #4


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    It's the question of quality. There are a number of properties you are looking for in a diode, and you just get better ones from silicone and even better from germanium.

    There are some carbon nano-materials that apparently make good semiconductors. So we might start using these in the future, but right now, it's prohibitively expensive. You get best quality for the money with silicone, which is why we use it.
  6. Jul 7, 2012 #5
    A strange comparison of silicon (silicone!) and germanium.
    I understand that the advantage of silicon over germanium was it's ability to operate at higher temperatures before the onset of intrinsic conduction.
    Germanium diodes have a smaller 'turn on' voltage than silicon diodes and this is an advantage when dealing with small signals.
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