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At 0k, why is fermi level halfway in bandgap?

  1. Jun 4, 2009 #1
    At 0k, why is fermi level halfway in bandgap??

    Fermi Level is defined as the maximum energy an electron posesses at 0k, which appears to be midway in the bandgap. I learnt that in the bandgap, there are no available states (i.e. no wavefunctions of electrons) hence, no electrons can possibly EXIST at the bandgap, so why is it that at 0k, some electrons have energy halfway between the band gap?? Does it mean that there are electrons halfway in the bandgap??

    Shouldnt the fermi level be at the TOP of the valence band instead?
     
  2. jcsd
  3. Jun 4, 2009 #2

    Kit

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    Re: At 0k, why is fermi level halfway in bandgap??

    physically, u cannot find the electrons between the band gap since there is no avaliable states within the bandgap. as u said the "Fermi Level is defined as the maximum energy an electron posesses at 0k". it just said that is the maximum possible energy that the electrons might have.
     
  4. Jun 4, 2009 #3
    Re: At 0k, why is fermi level halfway in bandgap??

    so, its just the ENERGY possessed by the electrons, which means the electrons in the valence band can have energy MID-WAY of the band gap but not be physically at the bandgap?
     
  5. Jun 4, 2009 #4

    Kit

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    Re: At 0k, why is fermi level halfway in bandgap??

    yes. this is what i think. u can imagine if there are some defected states below the fermi level but above the top of the valence band. electrons can be found there.
     
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