Fermi level in n-type or p-type semiconductors

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SUMMARY

The Fermi level in semiconductors is a critical concept that indicates the energy level at which the probability of finding an electron is 50%. In n-type semiconductors, the Fermi level is positioned closer to the conduction band due to the presence of additional electrons, while in p-type semiconductors, it is nearer to the valence band because of additional holes. Applying a voltage to semiconductor materials causes the Fermi level to shift, as voltage alters the energy states of electrons within the material.

PREREQUISITES
  • Understanding of semiconductor physics
  • Knowledge of n-type and p-type semiconductor characteristics
  • Familiarity with energy band theory
  • Basic principles of voltage and electric potential
NEXT STEPS
  • Study the concept of energy band diagrams in semiconductors
  • Learn about the effects of doping on semiconductor properties
  • Explore the relationship between Fermi level and temperature in semiconductors
  • Investigate the impact of external voltage on semiconductor behavior
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Students and professionals in electrical engineering, materials science, and physics who are looking to deepen their understanding of semiconductor theory and applications.

Cathyzhang
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Hi, everyone. I'm learning basic theories about semiconductors but can't quite understand the concept of Fermi level. is this just a imaginary energy level or true existence? and why Fermi level is close to the conduction band of n-type semiconductor and valence band of p-type semiconductor? the last question is, if applying a potential on the semiconductor materials, the Fermi level will shift up and down with the increase or decrease of the voltage-why?
thanks _Cathy:smile:
 
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is this just a imaginary energy level or true existence?
It does not have to be a possible energy level for electrons.
"imaginary" versus "true" is not physics.

and why Fermi level is close to the conduction band of n-type semiconductor and valence band of p-type semiconductor?
I think this is easier to see if you imagine an additional energy level in the bandgap. Where would it have to be to be 50% filled?
For n-type semiconductors, close to the conduction band, as you have additional electrons there.
For p-type semiconductors, close to the valence band, as you have additional holes there.

the last question is, if applying a potential on the semiconductor materials, the Fermi level will shift up and down with the increase or decrease of the voltage-why?
A voltage changes electron energies.
 
mfb said:
It does not have to be a possible energy level for electrons.
"imaginary" versus "true" is not physics.

I think this is easier to see if you imagine an additional energy level in the bandgap. Where would it have to be to be 50% filled?
For n-type semiconductors, close to the conduction band, as you have additional electrons there.
For p-type semiconductors, close to the valence band, as you have additional holes there.

A voltage changes electron energies.

Thanks! that's help :)
 

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