Talk:Light-emitting diode

This article was the subject of a Wiki Education Foundation-supported course assignment, between 1 April 2019 and 5 June 2019. Further details are available on the course page. Student editor(s): Abunc001 (article contribs).

Missing types

The article has very little information on the chronology and development of green (and yellow) LEDs. I remember that before the modern blue LEDs appeared there were "super reds" (dope with ZnO i believe), when were they developed? Now that there are bright red, blue and whites, have any bright greens, yelllows and oranges appeared to fill the gaps in those spectral areas? 150.227.15.253 (talk) 10:44, 19 March 2020 (UTC)

I believe yellow is just a shift up in the gap of GaAs_1-xP_x, increasing x. For green, GaP is indirect gap, but nitrogen doped GaP:N has a bound exciton which can recombine for radiative recombination. Some improvement in red came from using Ga_1-xAl_xAs instead. Gah4 (talk) 19:49, 19 March 2020 (UTC)

Are any LEDs or components made in the United States?

In this item from Consumer Reports, few lights were made in the USA. However, this was 2011, nine years ago. Does anyone with industry knowledge know if any LEDs and/or components are currently made in the USA? Thank you for your time, Wordreader (talk) 00:41, 18 July 2020 (UTC)

In CR, that would probably be light bulb replacements. This article is more about the either separately encapsulated devices, or the chips that go inside larger devices. My guess would be that chips might be made in the US, and sent away for encapsulation or device manufacture. The made in label is where the last parts of the assembly are done. Gah4 (talk) 19:38, 23 November 2020 (UTC)

LED Contact burning spots onto Skin?

I have a dark freckle like spot on my stomache where I used to rest my old laptop while it leaned on my legs. It's exactly where the orange LED on the front was in contact with me. There's no mark on any of my shirts, it was only in direct contact with my skin a few times. How long does exposure take before skin darkening occurs? — Preceding unsigned comment added by 207.112.55.242 (talk) 10:45, 23 November 2020 (UTC)

Orange LEDs don't make any UV, which might be related to skin darkening. But that would be months or years. Gah4 (talk) 19:34, 23 November 2020 (UTC)

Actually some LEDs use a UV LED and employ a phosphor to turn the UV into other colours. An orange phosphor sounds quite likely. I'd recommend you cover the LED with black tape to avoid this issue. GliderMaven (talk) 19:05, 2 February 2021 (UTC)

Pronunciation

User:GliderMaven has recently added the pronunciation /ɛlid/ for LED. No source was cited, and the pronunciation doesn't even make sense.

Lexico gives the pronunciation /ɛliːˈdiː/. But including this in the article isn't necessary per MOS:PRON because it's just the letters LED. Unless a source can be provided for /ɛlid/, I think there shouldn't be a pronunciation in the article at all. --Un assiolo (talk) 18:20, 2 February 2021 (UTC)

I checked and the pronunciation macro doesn't even support 'di' but it does support 'd'. You're really just being very tendentious indeed. And it does actually matter even within wikipedia is it 'an LED' or 'a led'? It goes beyond simple 'how do I pronounce it' and encroaches on grammar that is used in articles. How about you try not being a WP:DICK, yeah? GliderMaven (talk) 19:01, 2 February 2021 (UTC)

I have license to be a Dick, so let me emphasize his point that /ɛlid/ doesn't make any sense. What is it supposed to mean? It seems like it would suggest "elid". And actually, LED is sometimes pronounced "led"; it's not clear to me that we need to claim it's one or the other. Dicklyon (talk) 19:11, 2 February 2021 (UTC)

How shall we pronounce GASFET, Lord? Or JFET ? Or CMOS ?

Physics

Improving and expanding the section on Physics would greatly improve the quality and usefulness of this article.

Specific comment: "Also unlike most lasers, its radiation is not spatially coherent, so it cannot approach the very high brightnesses characteristic of lasers." makes no sense to me. I cannot understand how coherence affects intensity at all. The low divergence of the laser beam helps with intensity at long distances compared to other devices, but this has nothing to do with coherence.

More generally, I don't understand the physics explanation of how these work. Most semiconductor detectors work by a photon absorption "popping" an electron into the conduction band (ok, yes, and a hole, too). The "bias" as I understand it, is a voltage applied to help with the collection of electrons - conduction band electrons will be attracted to a + charged electrode. What I don't understand is how you reverse this to get an LED: Let's say you put a "-" charged electrode in the active area, and it can dump electrons into the conduction band with a voltage higher than the band gap. Let's say these electrons then emit light by falling back down to the ground state band. How is this anything but exactly the definition of pumping a lasing medium? Why isn't this a laser without the cavity? (Or are there a continuum of states above the band gap, and so stimulated emission (requiring exactly the right energy) will only rarely occur?)... Anyway, clarification of this and LED vs. laser physics would I think really improve the article. Thanks,

192.184.155.113 (talk) 22:54, 18 October 2021 (UTC)

Fairy Lights?

This term is unlinked to any article, no doubt because such an article doesn’t yet exist. Ought not it to have some explanation or defintion, e.g. decorative lighting? Is the term universally understood? Anyone ? --2001:44B8:3102:BB00:5188:52A3:D68:B969 (talk) 03:07, 23 November 2021 (UTC)