Conduction and valence bands in semiconductors

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SUMMARY

The discussion clarifies that the classification of conduction band states as s-type and valence band states as p-type is not universally applicable and is material-dependent. Specifically, in materials like copper (Cu), the conduction band is influenced by 3d electrons rather than 4s electrons, challenging the initial premise. Reference to a study indicates that in direct-gap semiconductors, states near the conduction-band minimum exhibit spherical symmetry akin to s-states, while valence band maxima states resemble p-orbitals.

PREREQUISITES
  • Understanding of semiconductor band theory
  • Familiarity with Bloch's theorem
  • Knowledge of k-space and its significance in solid-state physics
  • Basic concepts of electron orbitals (s and p types)
NEXT STEPS
  • Research the role of 3d electrons in transition metals and their impact on conduction bands
  • Study the symmetry properties of Bloch states in direct-gap semiconductors
  • Explore the implications of k-space in electronic band structure
  • Investigate the differences between direct and indirect bandgap semiconductors
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Physicists, materials scientists, and electrical engineers interested in semiconductor physics and electronic properties of materials.

Benevito
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Why is the conduction band state s-type and the corresponding valence band state p-type?
 
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This is not generally true. What material are you considering and where in k-space?
 
Benevito said:
Why is the conduction band state s-type and the corresponding valence band state p-type?

You really should cite where you get such a thing.

As DrDu as pointed, this is not true always and it is material dependent. For example, Cu, a common metal, has the 3d electrons as its valence shell, and thus, the 3d electrons that participate in the conduction band, not the 4s electrons. This already negates the starting point of your question.

Zz.
 
For example, here https://www3.nd.edu/~djena/kdotp.pdf it is stated that "For direct-gap semiconductors, for states near the conduction-band minimum (k = 0), the Bloch lattice-function possesses the same symmetry properties as a |S> state . In other words, it has spherical symmetry. The states at the valence band maxima , on the other hand, have the symmetry of p-orbitals"
 
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