As we read about Fermi energy, it is the energy of the highest occupied electrons. But if we look at the energy level diagram of semiconductor the Fermi level is situated somewhere between the valence band and the conduction band. The probability of the occupancy of the Fermi energy level is zero. If there enter some electrons in the conduction band due to thermal excitation conduction happens. My question is that how does the energy of the electrons whose energy is above the Fermi level, against the definition of the Fermi energy, are not called to be present at the Fermi energy level?
[Physics] Fermi level in metals and semicoductors
fermi-energysemiconductor-physics
Best Answer
To quote from a note in Ashcroft and Mermin's Solid State Physics book (p. 573 in the 1976 version):
Now, you might also want to look deeper into The chemical potential of an ideal intrinsic semiconductor (Mark R. A. Shegelski, American Journal of Physics 72, 676 (2004)) for a deeper look at the behavior of the chemical potential as a function of energy. In that paper it is shown that as $T \rightarrow 0$ the chemical potential goes to the bottom of the conduction band.