Valence and conduction bands in five band Hamiltonian

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Discussion Overview

The discussion revolves around the identification of valence and conduction bands in a five band Hamiltonian model, specifically in the context of a band structure plot for b12-borophene. Participants seek clarification on the nature of these bands and any special nomenclature associated with them, as well as the material's classification as an insulator, semiconductor, or metal.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that energy levels above 0 eV indicate conduction bands, while those below indicate valence bands.
  • There is confusion regarding the band structure diagram, which appears to show the material transitioning between insulator, semiconductor, and metal states as one moves across the plot.
  • One participant identifies the material in question as b12-borophene.
  • Another participant suggests that the band diagram indicates the material is a metal, with an indirect bandgap for certain directions and a direct bandgap for others.
  • References to external articles and studies are provided to support claims about the material's properties and band structure.

Areas of Agreement / Disagreement

Participants express differing views on the classification of the bands and the material's behavior, indicating that multiple competing perspectives remain without a consensus.

Contextual Notes

The discussion includes references to specific articles that may contain additional insights, but the interpretations of the band structure and material properties remain unresolved and dependent on the context of the diagrams presented.

Mohammad-gl
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Hello,
I have this band structure plot for five band Hamiltonian model. I want to know which bands are valence and which one is conduction bands. Also if they have any special name I like to know that.
Thank you.
 

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Mohammad-gl said:
Hello,
I have this band structure plot for five band Hamiltonian model. I want to know which bands are valence and which one is conduction bands. Also if they have any special name I like to know that.
Thank you.
Usually, if the energy is above ##0 eV## it is the conduction band, if below it is the Valence band. The confusing part of this diagram is that it looks like the material changes from insulator to semi-conductor to metal and back as you go from left to right. What is the material?
 
Last edited:
bob012345 said:
Usually, if the energy is above ##0 eV## it is the conduction band, if below it is the Valence band. The confusing part of this diagram is that it looks like the material changes from insulator to semi-conductor to metal and back as you go from left to right. What is the material?
this is b12-borophene material
 
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Mohammad-gl said:
this is b12-borophene material
Here is a reference to that material which has the band diagram color coded on page 5.

https://www.researchgate.net/publication/342185652_Two-Dimensional_Borophene_Properties_Fabrication_and_Promising_Applications/download
 
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bob012345 said:
Here is a reference to that material which has the band diagram color coded on page 5.

https://www.researchgate.net/publication/342185652_Two-Dimensional_Borophene_Properties_Fabrication_and_Promising_Applications/download
Thank you
 
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Based on these references and some more thought, I now think this band diagram shows this material is a metal but the overlapping bandgap is indirect for certain directions and direct for other directions.

This is Borophene specific;
"First-Principles Investigation of Borophene as a Monolayer Transparent Conductor "
https://www.osti.gov/pages/servlets/purl/1467636

This is a Nature review article;
"Bandgap engineering of two-dimensional semiconductor materials" https://www.nature.com/articles/s41699-020-00162-4.pdf
 

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