Talk:Valence and conduction bands

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Merge discussion

Copied from talk page of Valence band

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)

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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.

Metals

I got to this page through a link from electric current, though I am not so sure about the reasoning behind that link. In the introduction of this article, it indicates that in metals, a (implied one) band is partially filled. In many metals, bands overlap such that more than one are partially filled. Even more, when that happens, often one is more than half full, in which case the charge carriers are holes. Aluminum, the metal used for most power lines, has both hole and electron bands, and at high magnetic fields, a positive Hall coefficient. The electric current page could have ignored band structure, but instead mentioned charge carriers as electrons in a conduction band. Gah4 (talk) 21:29, 10 May 2017 (UTC)

Is this where we should explain impurity band conduction

Is this where we should explain impurity band conduction in silicon ? and is "blocked impurity band conduction" a thing ? (Used in Spitzer Space Telescope and JWST). Band_diagram#Energy_levels briefly mentions E_Imp. - Rod57 (talk) 12:41, 27 December 2021 (UTC)

Probably not. The usual single photon detector is the avalanche photodiode. And usually dopant density is low enough, such that there isn't a lot of overlap, and so isn't usually described as a band. (But they are usually described in terms of how far from the band edge they are.) More guessing now, it is cold enough that the impurity states are not (thermal) ionized, but are by accelerating charge carriers. That is, avalanche effect from 50meV states, instead of the whole gap. My thought is that it could go in Visible Light Photon Counter but not here. Gah4 (talk) 22:22, 15 February 2022 (UTC)

I'm wary of burying an explanation of impurity band conduction in Visible Light Photon Counter as IBC is a physics phenomenon, whereas VLPCs (and APDs) are artificial devices. (As a phenomenon, it could also be covered in electronic band structure but the latter page is written at far too high a level, IMO).

Pragmatically though, the sticking point is needing someone with the expertise to write a few accessible, correct paragraphs to have the time to do so. Good content can easily be moved around afterwards! Louis Knee (talk) 20:14, 12 March 2022 (UTC)

I think (but really don't have the expertise) that impurity band conduction and blocked impurity band conduction are based on similar physical principles, but the terms are used with respect to devices based on patents held by Rockwell and Raytheon respectively. Louis Knee (talk) 20:20, 12 March 2022 (UTC)

Maybe the distinction there is historical; newer references do mix things around more. Louis Knee (talk) 20:42, 12 March 2022 (UTC) Louis Knee (talk) 20:42, 12 March 2022 (UTC)

References

indirect and negative gap?

Should somewhere, maybe here, explain indirect gap, and especially that some can have a negative indirect gap? Gah4 (talk) 05:54, 16 February 2022 (UTC)

OK, I found it in: Direct_and_indirect_band_gaps#Other_aspects. Gah4 (talk) 06:00, 16 February 2022 (UTC)