Talk:Valence band

Untitled

This article told me nothing at all about what I wanted (brought here from Holographic memory).

I've edited the Holographic memory article to hopefully address this problem--Tiresais 16:21, 19 June 2006 (UTC)

Zero temperature? Don't you mean ground level or else their basic orbital shell?

I think it was meant to mean absolute zero, but I don't know enough on the topic to change it. --Snaxe920 07:51, 5 February 2006 (UTC)

I'm not quite sure either, I presume it would be the Valence band since it takes energy for electrons to move into the Conductance band. At Absolute zero they have minimal internal energy. Editing now--Tiresais 07:58, 25 June 2006 (UTC)

I think it might be worth merging the Valence band and Conduction band articles together, since there is a fair bit of overlap. Arch 10:36, 24 September 2007 (UTC)

   I second  —Preceding unsigned comment added by 193.60.83.241 (talk) 18:42, 1 May 2008 (UTC) 

Why stating that there is no band gap between the valence and conductive bands in metals?

See the article Semiconductor - there is a picture of energy levels of Mn cleary showing the gaps. It comes from solving the problem about the dispersion law in solids. We do not count any properties of material, and still have band gaps. Cramur (talk) 00:39, 23 February 2008 (UTC)

--> I think the picture tried to explain that there is no band gap between conduction bands and valence bands of 'conductors' not all metals. Chemicalwolf —Preceding undated comment added 13:13, 4 November 2010 (UTC).

Reference and Stub tags

This article needs references and citations for its sources of material. Its current form is lacking organization for its material. It badly needs expansion, re-organization, some verifiable sources. The reference and stub tags have been placed on this article. Venny85 19:04, 6 April 2008 (UTC)

Sorry, I probably shouldn't have deleted the unreferenced tag. The stub tag was properly deleted, though. This article is beyond stub length. Per WP:STUB, a "stub" is an article containing only a few sentences of text. Once an article gets beyond stub length (certainly by the time it fills a full screen), the stub tag should be removed.--Srleffler (talk) 23:54, 6 April 2008 (UTC)

As a general rule, I find editing programs that consist of adding tags like {{unreferenced}} to large numbers of articles are not very helpful. Most Wikipedia articles lack references, and even the ones that have a few references could use more. The unreferenced tag is best used to flag articles where there is a particular need for references. If one is adding this tag to many articles rapidly, the time would probably be better spent actually working on improving one of those articles instead.--Srleffler (talk) 23:57, 6 April 2008 (UTC)

valence electrons bound to individual atom?

The sentence I quote below from the introduction of the article bothers me, I think it might be untrue or just circumstantially true. Here's the sentence. "The valence electrons are bound to individual atoms, as opposed to conduction electrons (found in conductors and semiconductors), which can move freely within the atomic lattice of the material."

In fact, we know (and the article mentions near the end) that holes in the valence band are current carriers like the electrons of the conduction band are. Now, hole movement inside a material is just an adequate and convenient (because simple) way to describe electron movement in a nearly fully occupied landscape of energy states: what makes the hole move is that a nearby electron "jumps" into the hole, leaving a hole in the energy state it used to occupy, and the net obtained result can be conveniently described as a movement of the hole.

Now, imagine we have a pure semiconductor which gets its conductivity from thermal fluctuations. We have as many holes in the valence band as we have electrons in the conduction band. Both the conduction band and the valence band participate to this conductivity, and I suspect to a similar if not identical extent, because both contain the same number of current carriers.

That's why I wouldn't say that valence electrons are closely bound to individual atoms to begin with. But there's more. Take the case of a silicium crystal for example. So, the valence band is the highest range of electron energies at which electrons are present at absolute zero. By this definition, this makes the valence band be made of the lower energy levels that arise from the recovery of the higher energy atomic orbitals between neighbouring atoms in the crystal lattice... and then the conduction band is made of the higher energy levels that arise from the recovery of the higher energy atomic orbitals between neighboring atoms in the crystal lattice (Si makes 4 covalent bonds like carbon, which means all the electrons of its upper atomic energy states participate in valence bonds in the crystal). The valence electrons are not bound to individual atoms any more than conduction electrons are bound to a single atom. I'm quite positive this is true for silicium crystals at least (might be true for others, I'm not sure).

This leads me to another paragraph from the article, which I quote: "Semiconductors and insulators owe their low conductivity to the properties of the valence band in those materials. The number of electrons is precisely equal to the number of states available up to the top of the valence band.[clarification needed] There are no available states in the band gap. This means that when an electric field is applied, the electrons cannot increase their energy (i.e., accelerate) because there are no states available to the electrons where they would be moving faster than they are already going."

Many problems in the above. First, as stated, we have a "low conductivity," which is not a zero conductivity, except possibly in a pure semiconductor at absolute zero. I guess it would be more technically correct and less misleading to first explain why we'd have no conductivity at absolute zero, and then explain why we have low but non-zero conductivity above absolute zero. The last sentence gets very weird by calling upon electron kinetic energy, because I bet the orbital kinetic energy of electrons at any given moment is huge in front of any kinetic energy per electron that might arise from macroscopic electric currents. Anyway, my take is that it would be much clearer and valid to drop the "acceleration" justification altogether and call upon the exclusion principle to justify that no current can occur within a completely full valence band, which at the moment has to be read in-between the lines.ThorinMuglindir (talk) 21:46, 7 July 2012 (UTC)

Positive ion notation

Forgive my ignorance on this subject, but is the proper notation for the electron configuration of a positively-charged lithium ion really supposed to be 1s² (e⁺) ? When I see the e⁺, it makes me think of a positron. — Preceding unsigned comment added by Rogermw (talk • contribs) 19:59, 19 September 2012 (UTC)

Much/most of the article is plain wrong.

I don't quite know where to start - things like "valence electrons are bound to individual atoms" (nonsense - if this was the case, there would be no band in the first place!), or "valence electrons (as opposed to conduction electrons)" - a valence electron can be a conduction electron at the same time (if the band is not filled). Similarly, the conductivity of a metal does not depend on the "capability to flow electrons from valence band to conduction band" - in a metal, the valence band generally IS the conduction band, as is (correctly) implied by the definition of "valence band" in the summary of the article.

I suspect the concept of valence band may be well covered in other articles on solid state physics (e.g. the article on electronic band structure; it may not be worth putting in the effort to salvage this article (read: rewrite from scratch) if the ground is already well covered in other articles. — Preceding unsigned comment added by 27.96.110.66 (talk) 12:15, 15 November 2012 (UTC)

Please, make it better. I was so confused when I thought of Bloch wave solution of Schrodinger equation for an electron in the periodic potential of the atomic lattice. The solution says that the electron shall belong to any atom, without knowing the exact form of the solution.Gamebm (talk) 16:38, 27 November 2012 (UTC)

Confusing and wrong. & Proposed deletion

As I noted in Talk:conduction band and as others noted in some of the above talk posts, these articles are confusing and even outright incorrect.

I propose deleting this article and conduction band, redirecting them to a fixed version of the band theory article. --Nanite (talk) 15:29, 11 May 2013 (UTC)

Merge valence and conduction band articles

The following discussion is closed. Please do not modify it. Subsequent comments should be made in a new section. A summary of the conclusions reached follows.

The result of this discussion was to merge. This article could be more specialized to explain what the bands are which the electronic band structure does not. There could be content transfer between the two articles. In my opinion the bands play a role in insulators and semimetals too (although arguably not metals). Officer781 (talk) 04:28, 2 June 2015 (UTC)

---

The two articles are rather short and contain significant overlap (one cannot be understood without the other). Some materials, such as semiconductors, feature both in tandem (movement of electrons in conduction band, movement of holes in valence band). As such, I propose that the two articles be merged into an article titled "Valence and conduction bands" which not only discusses the two bands individually, but also the commonalities between the two and how they can work in tandem. A potential extension of such an article would include the different types of conduction valence band combinations (metal, semimetal, semiconductor, etc). Would like to cite the unified page HOMO/LUMO as precedent.--Officer781 (talk) 11:05, 25 May 2015 (UTC)

Question: What would be the relation between electronic band structure and "valence and conduction bands"? I mean, what would be in each but not the other? If there isn't a logical division then maybe all of them should be merged?

I would actually propose something a bit different: Instead of what we have now (conduction band and valence band and electronic band structure), we could just have two articles: semiconductor valence and conduction bands and electronic band structure. I don't think an article about valence and conduction bands really makes sense outside the context of semiconductors. I mean, there are lots of interesting things to say about the electronic band structure of metals, but these things are not really in the category of "valence and conduction bands", and in fact those terms aren't really used for metals. (Are they?) Likewise, electronic transport in insulators is a fascinating topic (Fowler-Nordheim, Poole-Frenkel, space-charge-limited transport, polarons, etc. etc.) but the conduction and valence band play a relatively small role, compared to their central importance in semiconductor electronic transport.

The article semiconductor valence and conduction bands would have some overlap with band gap but I don't think an excessive amount.

I'm just brainstorming, I haven't thoroughly thought these things through. :-D --Steve (talk) 13:42, 26 May 2015 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.