0:31 Occupation of states, 1:23 Fermi level, 3:29 the Fermi Function, 6:19 Electrons ans holes, 7:12 Conduction band, 13:58 Valence band, 10:23 Nondegenerate semiconductors, 11:19 Energy band diagram of an intrinsic semiconductor, 12:04 Energy band diagram and carrier densities
The same time stamps but line-broken 0:31 - Occupation of states 1:23 - Fermi level 3:29 - The Fermi Function 6:19 - Electrons and holes 7:12 - Conduction band 13:58 - Valence band 10:23 - Nondegenerate semiconductors 11:19 - Energy band diagram of an intrinsic semiconductor 12:04 - Energy band diagram and carrier densities
Mark, On your fermi probability diagram, you have defined the fermi level at 1/2 probability point and fixed at different temperatures. But isn't the fermi level dependent on temperature too? Shouldn't the E(f) position also move on the E axis as the temperature varies?
Thanks for the question. You are correct - the position of the Fermi level does change with temperature. That?s a little hard to show on a plot like this. The point here is that as the temperature increases, the transtion from f = 1 to f = 0 occurs over a wider range of energies - always centered about the Fermi energy. Lecture 3.5 discusses temperature dependence a bit. See slide 24 in L3.5.
The probability of occupation at E=Ef is always 1/2, regardless of temperature. The graph of probability of occupation (the fermi function) is different from the band diagram graph, where you see the fermi level in relationship to the bands.
0:31 Occupation of states, 1:23 Fermi level, 3:29 the Fermi Function, 6:19 Electrons ans holes, 7:12 Conduction band, 13:58 Valence band, 10:23 Nondegenerate semiconductors, 11:19 Energy band diagram of an intrinsic semiconductor, 12:04 Energy band diagram and carrier densities
The same time stamps but line-broken
0:31 - Occupation of states
1:23 - Fermi level
3:29 - The Fermi Function
6:19 - Electrons and holes
7:12 - Conduction band
13:58 - Valence band
10:23 - Nondegenerate semiconductors
11:19 - Energy band diagram of an intrinsic semiconductor
12:04 - Energy band diagram and carrier densities
Thanks a lot
Mark,
On your fermi probability diagram, you have defined the fermi level at 1/2 probability point and fixed at different temperatures. But isn't the fermi level dependent on temperature too? Shouldn't the E(f) position also move on the E axis as the temperature varies?
Thanks for the question. You are correct - the position of the Fermi level does change with temperature. That?s a little hard to show on a plot like this. The point here is that as the temperature increases, the transtion from f = 1 to f = 0 occurs over a wider range of energies - always centered about the Fermi energy.
Lecture 3.5 discusses temperature dependence a bit. See slide 24 in L3.5.
The probability of occupation at E=Ef is always 1/2, regardless of temperature. The graph of probability of occupation (the fermi function) is different from the band diagram graph, where you see the fermi level in relationship to the bands.