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Accessing electrons from the Fermi Sea?

  1. Sep 23, 2013 #1
    Recently a few friends and I were discussing the Fermi sea.

    One friend made the statement that if you could access the electrons from the Fermi Sea you could use the material you accessed them from as an electron source. Didn't make sense to me but it got me wondering.

    My question is, What would it take? Why hasn't it been done/tried before?
    Last edited: Sep 23, 2013
  2. jcsd
  3. Sep 24, 2013 #2
    Well, I am a little confused. The free electrons in a metal makes up the Fermi sea, and one can immediately use them as an electron source by shining light on the metal by photoemission.

    Was this the question?
  4. Sep 24, 2013 #3
    Sorry, we were talking about removing them from a semiconductor material.

    I know that in metals the conduction band and Fermi level overlaps, but in semiconductors there is a potential barrier that separates them.

    My friend said if you could find a way to get those electrons across the barrier you could use the semiconductor as a separate electron source. Just got me thinking, perhaps there is a way you could really do this...?
  5. Sep 24, 2013 #4


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    I'm not quite sure what you're getting at. Many semiconductor devices work on this exact principle. Examples include semiconductor transistors, solar cells, and photoresistors. Electrons are given enough energy to jump the band gap and go from the valence band to the conduction band.
  6. Sep 25, 2013 #5


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    I'm confused also.

    One of my area is high-QE photocathodes. All of the material (and I mean ALL) that we use to make these high-QE photocathodes are semiconductors. And we are using light sources to get those electrons in the valence band of the material.

    And this is nothing new. Material such as the antimonides (eg: CsKSb, etc.) have been used in phototubes since the 50's.

    So yes, we HAVE been "accessing electrons from the Fermi sea".

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