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Why amorphous phase materials have wider bandgap?

  1. Aug 21, 2004 #1
    I'm wondering why the amorphous phase materials have wider bandgap compared to its crystalline phase. To my best knowledge, the bonding mechanism does not changed as the material transform from crystalline phase to amorphous phase. So what causes it has larger bandgap?

  2. jcsd
  3. Aug 21, 2004 #2

    I think (not to sure though) it has something to do with the fact that the periodic Bloch wave-functions do not account for the forbidden energy as much as they used to in a cristal-lattice.

    The band gap is there because the electrons can acquire two different potential energy-values when passing through the periodic potential of the positive lattice ions

  4. Aug 21, 2004 #3
    Last edited by a moderator: Apr 21, 2017
  5. Aug 26, 2004 #4
    Thanks to Marlon and Kurious...

  6. Sep 22, 2004 #5
    Search for "Anderson localization" and "band edge states".
  7. May 1, 2009 #6
    Are you sure amorphous materials have wider bandgap? I think they should have narrower Eg due to the band edge tailing effect.
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