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Concentrations of electrons in intrinsic semi-conductor

  1. Nov 25, 2012 #1
    Hi, i've just started using the formula for the abovie which is given as:

    n t^3/2 exp(Eg/2kBT)

    however instead of n= I think the sign is n is proportional, like this ∞

    I was wondering which would be correct?

  2. jcsd
  3. Nov 25, 2012 #2


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    Science Advisor

    Yes it's definitely proportional to, not equals. That is, [itex]n \propto T^{3/2} \exp(Eg/(2k_BT))[/itex].

    You can "see" this easily enough by looking at the dimensions (units) of each side of the equation. The term "n" is a density, and therefore [itex]m^{-3}[/itex] (or [itex]cm^{-3}[/itex] etc), whereas the unit on the RHS is T^1.5.

    The "T^(3/2)" factor is merely the temperature dependent part of the equation for the "effective density of states referred to the conduction band edge", if you want to google that.
    Last edited: Nov 25, 2012
  4. Nov 25, 2012 #3
    I see now, thanks :)
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