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Band theory of solids

  1. Oct 31, 2015 #1
    Do electrons in conduction band are only responsible for current? Don't the electrons in partially filled valence band capable of moving contribute to current?
    Material discussed-metals(conductors)
     
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  3. Oct 31, 2015 #2

    ZapperZ

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    Where is this partially-filled valence band in a metal?

    Zz.
     
  4. Oct 31, 2015 #3
    In metals either of the two cases exists-
    1. Conduction band is partially filled and the valence band is partially empty. OR
    2. Conduction and valence band overlap.
     
  5. Nov 1, 2015 #4

    ZapperZ

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    Show me the band structure where the valence band is partially empty.

    Zz.
     
  6. Nov 1, 2015 #5
     

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  7. Nov 1, 2015 #6

    ZapperZ

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    This references are utterly confusing (what text are you using that has a typo of valence being replaced by "balanced"). The 2nd one, especially, is trying to differentiate between a metal and a semiconductor! We know about unfilled valence band for semiconductor. What I'm asking is for you to show me an example on the band structure of a metal that has a partially empty valence band.

    I bet you that what is being described here is the difference between an insulating and a conducting state of a semiconductor! This is not a metal! A semiconductor may be conducting, but it is STILL not a metal! The valence band of a metal doesn't play a role in its charge transport properties. A semiconductor does!

    I suggest you look very, VERY carefully at what you are reading and the terminology that you are using.

    And please read this thread on why I consider the explanation of "band overlap" is flawed:

    https://www.physicsforums.com/threads/how-does-band-structure-lead-to-metals-insulators.839172/

    Zz.
     
  8. Nov 2, 2015 #7

    DrDu

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    In semi-metals like Bismuth and graphite, you encounter the situation that there is one band almost filled and one band almost empty. Personally, I generally would avoid speaking of conduction and valence bands as this termini are clearly missleading.
     
  9. Nov 3, 2015 #8
    The electrons in valence band move with their corresponding group velocities but they don't conduct any charge because they move in different directions. I think it is possible to have conduction by the electrons in partially filled valence band provided that the symmetry of distribution in the band is broken.
     
  10. Nov 3, 2015 #9

    DrDu

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    If this were true, p-doped semiconductors would be isolators, too.
     
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