Do semiconductors have to have a full valence band?

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Discussion Overview

The discussion revolves around the characteristics of semiconductors, specifically whether they must have a full valence band. Participants explore the relationship between atomic structure and electronic band theory, questioning the definitions and implications of valence shells and bands.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant notes that their book states semiconductors have a full valence band, but questions this in light of the outer shell configurations of Silicon and Germanium.
  • Another participant clarifies that a valence shell differs from a valence band, suggesting that atoms with partially empty valence shells can still exhibit full valence bands due to band formation in solids.
  • A participant expresses confusion regarding the relationship between azimuthal quantum numbers and valence bands, indicating a potential misunderstanding of the concepts presented in their book.
  • One participant emphasizes the distinction between single atoms and groups of atoms, implying that the behavior of materials differs from that of individual atoms.
  • A later reply expresses strong dissatisfaction with the explanations provided, indicating a lack of clarity or agreement on the topic.

Areas of Agreement / Disagreement

The discussion features multiple competing views regarding the definitions and implications of valence bands and shells, and remains unresolved with no consensus reached among participants.

Contextual Notes

Participants express uncertainty about the definitions of valence bands and shells, and how these concepts apply to semiconductors. There are indications of missing assumptions and potential misunderstandings regarding the relationship between atomic structure and electronic properties.

nonequilibrium
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Hello,

In my book it says that semiconductors have a full valence band and a fermi energy somewhere in between that valence band and the conduction band. But its two examples of semiconductors, crystals of Silicon or Germanium, have a [tex]3s^2 3p^2[/tex] resp. [tex]4s^2 4p^2[/tex] outer shell, so surely they can't result in a full valence band?

Thank you.
 
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A valence shell is different from a valence band. It's possible for atoms with partially empty valence shells to have full valence bands because the energy levels of the electrons widen into bands and can split when the atoms are brought close together, as is the case with a solid.
 
Hm, I thought that each azimuthal quantum number [tex]l[/tex] corresponded to one valence band, that is what my book is implying anyway, but I suppose that's wrong then.

Thank you.
 
well :) A single atom is one thing, and a group of closed atoms (material) is another thing.
 
wow, that's the worst explanation I've ever had about anything
 

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