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Depletion Layer Confusion

  1. Jan 2, 2010 #1
    In p-n junction formation,
    Electron from n-type combine with holes on p-type to form negative ions leaving behind positive ions on n-type.

    Now, why aren't these negative ions and positive ions attracted by electron on n-type and holes on p-type respectively?

    They restrict further movement of electrons or holes but why these ions themselves aren't moved with repulsive forces?

    Both the above factors would've uniformly distributes the negative ions on positive side and positive ions on negative side. But this doesn't happens... why?
  2. jcsd
  3. Jan 2, 2010 #2


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    I don't fully understand your question but I think you're confused because you don't realize there is both an electric field and a diffusion force on the charge carriers, and in the space charge region, with no external electric field, they balance.

    This page is very good and has more details (and lot's of great images).
    See Figure A in particular.
  4. Jan 2, 2010 #3


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    Gold Member

    Last edited by a moderator: Apr 24, 2017
  5. Jan 2, 2010 #4
    Thanks :)

    Yes, this was what I was looking for. Thanks :)
    Last edited by a moderator: Apr 24, 2017
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