prateeksikka
- Jun 19, 2004
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fermi level is the level of energy where there is a 50% possibility to locate an electron or simply
its the energy which most of` the electrons have .
it depends on doping concentration ....
its the energy which most of` the electrons have .
it depends on doping concentration ....
AmericanCircuitTech
- Feb 1, 2011
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Regarding semiconductors where is fermi level(http://en.wikipedia.org/wiki/Fermi_level )located in an intrinsic,p type,n type semiconductors and why?
In an intrinsic semiconductor, n = p. If we use the band-symmetry approximation, which assumes that there are equal number of states in
equal-sized energy bands at the edges of the conduction and valence bands,
n = p implies that there is an equal chance of finding an electron at the conduction band edge as there is of finding a hole at the valence band edge:
f(EC) = 1 − f(EV )
For an n-type semiconductor, there are more electrons in the conduction band than there are holes in the valence band. This also implies that the probability of finding an electron near the conduction band edge is larger than the probability of finding a hole at the valence band edge. Therefore, the Fermi level is closer to the conduction band in an n-type semiconductor.
n − type : f(EC) > (1 − f(EV )) ) |EC − EF | < |EF − EV | ) EF > Ei (13)
For a p-type semiconductor, there are more holes in the valence band than there are electrons in the conduction band. This also implies that the probability of finding an electron near the conduction band edge is smaller than the probability of finding a hole at the valence band edge. Therefore, the Fermi level is closer to the valence band in an n-type semiconductor.
p − type : f(EC) < (1 − f(EV )) ) |EC − EF | > |EF − EV | ) EF < Ei
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In an intrinsic semiconductor, n = p. If we use the band-symmetry approximation, which assumes that there are equal number of states in
equal-sized energy bands at the edges of the conduction and valence bands,
n = p implies that there is an equal chance of finding an electron at the conduction band edge as there is of finding a hole at the valence band edge:
f(EC) = 1 − f(EV )
For an n-type semiconductor, there are more electrons in the conduction band than there are holes in the valence band. This also implies that the probability of finding an electron near the conduction band edge is larger than the probability of finding a hole at the valence band edge. Therefore, the Fermi level is closer to the conduction band in an n-type semiconductor.
n − type : f(EC) > (1 − f(EV )) ) |EC − EF | < |EF − EV | ) EF > Ei (13)
For a p-type semiconductor, there are more holes in the valence band than there are electrons in the conduction band. This also implies that the probability of finding an electron near the conduction band edge is smaller than the probability of finding a hole at the valence band edge. Therefore, the Fermi level is closer to the valence band in an n-type semiconductor.
p − type : f(EC) < (1 − f(EV )) ) |EC − EF | > |EF − EV | ) EF < Ei
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OK i will try to help .!!!!
as we know the Fermi level is a limit to the transfer of electrons from the valence band to the conduction band. so when the electron is below the Fermi level position then he will remain Valence electron band but when it is above the Fermi level position then he will be in the conduction band but if electron is located at the Fermi level position then he has the same chance to be in the conduction band / valence band.
as we also know that the position of the Fermi level is very dependent of the doping elements were given at a time element that is type (electron majority carriers), the Fermi levels will be more toward the conduction band, the more doping is given, the more she approached conduction band. contrary to p-type
to more clearly you can see the image that I attach
source: microelectronics an integrated approach (international edition)
I hope this answer can help you
View attachment 41319
as we know the Fermi level is a limit to the transfer of electrons from the valence band to the conduction band. so when the electron is below the Fermi level position then he will remain Valence electron band but when it is above the Fermi level position then he will be in the conduction band but if electron is located at the Fermi level position then he has the same chance to be in the conduction band / valence band.
as we also know that the position of the Fermi level is very dependent of the doping elements were given at a time element that is type (electron majority carriers), the Fermi levels will be more toward the conduction band, the more doping is given, the more she approached conduction band. contrary to p-type
to more clearly you can see the image that I attach
source: microelectronics an integrated approach (international edition)
I hope this answer can help you
View attachment 41319
Last edited by a moderator:
Kevin Weddle
- Feb 23, 2004
- 1,620
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- Feb 23, 2004
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- 1,620
Fermi level and energy bands have to play small roles. Current value is regardless of valence bands or conduction bands or the energy required. The reason is because energy levels applied to conductors and semiconductors are very high. Electrons can move to any energy level with a change in temperature.
J
Johnsteave7
- Jan 1, 1970
- 0
The Fermi level EF of an intrinsic semiconductor lies in the middle of energy gap. This shows that free electrons and holes have equal concentrations.
For N type materials donor atoms of an n-type semiconductor get ionized at a given temperature to get estimation of Fermi level.
For P type the density of acceptor atoms far exceeds the density of donor atoms.
Every acceptor atom has accepted one electron from the valence band.
For further emphasize followed by www.ece.umd.edu/~dilli/courses/enee313.../supplement1_carrierconc.pd.Although the semiconductor materials act free nature so you may visit Materials those help you to know.
Thanks!!!!
For N type materials donor atoms of an n-type semiconductor get ionized at a given temperature to get estimation of Fermi level.
For P type the density of acceptor atoms far exceeds the density of donor atoms.
Every acceptor atom has accepted one electron from the valence band.
For further emphasize followed by www.ece.umd.edu/~dilli/courses/enee313.../supplement1_carrierconc.pd.Although the semiconductor materials act free nature so you may visit Materials those help you to know.
Thanks!!!!
R
remonx6
- Jan 1, 1970
- 0
Fermi level of P type and n type intrinsic materials found where the valance band and conduction band implies in the middle positions. where the energy band gap confined to valance and conduction band gap.
