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How are transistors and QM tied

  1. Feb 11, 2014 #1
    I know that transistors work using QM, but I dont know how, can someone explain this to me?
     
  2. jcsd
  3. Feb 11, 2014 #2

    Simon Bridge

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    Practically everything special about them is owed to some quantum effect - so that would be a lot of typing.
    Tell us first how you understand transisters working and then I'll show you the quantum :)

    Meantime there are a lot of explanations online at various levels.
    http://www.madsci.org/posts/archives/2000-03/952639215.Ph.r.html
    http://spectrum.ieee.org/semiconductors/devices/the-tunneling-transistor

    Technically, of course, everything works using QM - it's just that some things exploit the special nature of QM more than others. The smaller the transistor (or anything) the more important the details of quantum effects become.
     
  4. Feb 11, 2014 #3

    ZapperZ

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    Transistors are made of semiconductors. The physics of semiconductors themselves can only be described using quantum mechanics. This is how one can understand the various types of doped semiconductors (n-type and p-type).

    Next, when you sandwich these semiconductors together to form junctions (np, pn, npn, pnp, etc.) that make up a transistor, how they behave and their properties can only be described via quantum mechanics. This includes not only how the charges are transported, but also in describing tunnel diodes properties, a purely quantum phenomenon.

    Zz.
     
    Last edited: Feb 11, 2014
  5. Feb 12, 2014 #4
    Are semi conducters in a state of superposition? I know its an exchane of electrons. Thanks
     
  6. Feb 12, 2014 #5

    ZapperZ

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    What exactly does that mean?

    You need to remember that "superposition" comes "naturally" out of the way QM describes a system. It is almost an inevitable part of the description. We almost never ask such a question.

    The semiconductor is not in a state of superposition. The charge carriers are, at least from the description used to arrive at the band structure.

    I think, anything that goes beyond what I had answered will go over your head and it will simply be nothing more than random bits and pieces without any coherent picture.

    Zz.
     
  7. Feb 12, 2014 #6

    Simon Bridge

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    Pretty much as ZapperZ said - everything can be represented as a superposition of quantum states. You need to be more specific. What is your interest?

    I don't think it is useful to consider the quantum state of the whole semiconductor when you are thinking about how it works. Better to think of the state of the individual charge carriers.
    In operation, they are always represented as superpositions of some kind.

    Don't know what you mean by "exchange of electrons". I suspect you are confusing terminology. Understanding about electrons and holes is essential to understanding semiconductors: gives you a starting place for searching the web :)

    However, I believe your original question has been answered.
     
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