Understanding Fermi Level in Silicon: Valence and Conduction Bands Explained

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Discussion Overview

The discussion revolves around the concept of the Fermi level in silicon, specifically addressing its position in relation to the valence and conduction bands, as well as the width of the band gap. Participants explore both intrinsic and doped silicon contexts, including mathematical representations related to the Fermi level.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants state that intrinsic silicon has its Fermi energy at the center of the band gap, indicating equal concentrations of holes and electrons.
  • Others assert that doping silicon shifts the Fermi energy towards either the valence band or the conduction band, depending on the type of doping.
  • Participants confirm that the band gap for silicon is 1.12 eV, with some providing a visual reference to illustrate this point.
  • There is a request for clarification regarding the equation related to the Fermi level, indicating some participants do not fully understand it.
  • One participant emphasizes that the Fermi level for undoped silicon is positioned between the conduction band and the valence band.

Areas of Agreement / Disagreement

Participants generally agree on the value of the band gap for silicon being 1.12 eV and the position of the Fermi level in undoped silicon. However, there is some uncertainty and confusion regarding the mathematical representation of the Fermi level and its implications in different doping scenarios.

Contextual Notes

Some participants express uncertainty about the equation used to calculate the Fermi level, indicating a need for further clarification on its derivation and application.

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what I've been told there is two groups of energy levels called the valence and the conduction band.

what is the fermi level for silicon?
how wide is the band gap for silicon?
 
Last edited:
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Well, if we are talking about intrinsic silicon (undoped silicon) then the fermi energy is directly in the center of the band gap. This means that the concentration of holes and electrons is equal. Doping the silicon will move the fermi energy towards the valence band or the conduction band depending on the doping.

The band gap for silicon is 1.12eV

E_f - E_i = kT ln\frac{n}{n_i}
 
is 1.12eV the width of the band gap or the fermi level?
what is the fermi level for undoped silicon?
 
Last edited:
That is the width of the band gap as I stated in the last post. The fermi level for undoped silicon lies directly inbetween the conduction band and the valence band. I have also provided you with the equation that you need to find the fermi level.
 
i don't understand the equation. please explain how you find the fermi level
 

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