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Pn junction: fermi enery

  1. Nov 13, 2006 #1
    Why is it that when no voltage is applied across the pn junction, the fermi energy is the same for both regions?
  2. jcsd
  3. Nov 13, 2006 #2


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    If there are no other forces (gradients in thermal or mechanical potentials) acting on the particles (charge carriers), then a difference in chemical potentials will give rise to a particle current. So, the system can not be in equilibrium unless the chemical potentials are equal.
  4. Dec 2, 2006 #3
    Because that system is in thermodynamic equilibrium after contact between the p and n type SC is made. There is no net charge transfer over the interface and this is expressed by a fermi level (which is in fact the chemical potential in the case of a SC and insulator) that is horizontal and equal throught the entire interface.

    Last edited: Dec 2, 2006
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