Timeline for Why do LDR photocells use CdS and CdSe?
Current License: CC BY-SA 4.0
7 events
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| May 30, 2019 at 22:47 | comment | added | Voltage Spike♦ | @analogkid the bandgap changes the resistance in CdS the mechanism is not the same as transistors, it is still a semiconductor. When a photon hits CdS, it jumps the bandgap and current flows | |
| May 28, 2019 at 20:48 | comment | added | Hearth | @AnalogKid I am referring to a photoresistor. That doesn't make it not a semiconductor. The way it works is in fact completely predicated on carrier pair generation by photon absorption; an electron in the valence band absorbs a photon and becomes a free electron-hole pair, and since conductivity is proportional to the carrier concentration, conductivity increases as more carrier pairs are generated. Importantly, this is a defining characteristic of semiconductors; this type of carrier generation does not occur in metals or insulators. | |
| May 28, 2019 at 16:43 | comment | added | AnalogKid | I took the term "photocell" to mean a photoresistor, not a solar cell or any other Cds use. In that context, CdS has no directionality or polarity. Whatever its underlying physics, it does not "behave" the same way a photodiode or phototransistor does. | |
| May 28, 2019 at 15:58 | comment | added | Voltage Spike♦ | CdSe is a class II-IV semiconductor en.wikipedia.org/wiki/Cadmium_selenide CdS also has a bandgap en.wikipedia.org/wiki/Cadmium_sulfide | |
| May 28, 2019 at 14:58 | history | edited | Hearth | CC BY-SA 4.0 |
Formatting for clarity
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| May 28, 2019 at 14:55 | comment | added | Hearth | They're not semiconductors? That's news to me. And contradicts my understanding of how they even work. Can you provide citations for your claims here? What makes them more reliable? How can they handle higher voltages than silicon? How does the dynamic range compare to alternative devices? | |
| May 28, 2019 at 14:05 | history | answered | AnalogKid | CC BY-SA 4.0 |