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what is fermi level and....


vamshi
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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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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

post-60973-14279144286595_thumb.png

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  • 2 years later...
Guest Johnsteave7

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!!!!

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  • 2 months later...
Guest remonx6

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.

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