Timeline for Silicon Diode Threshold Voltage 0.7
Current License: CC BY-SA 4.0
16 events
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| Apr 27, 2021 at 1:22 | history | edited | wbeaty | CC BY-SA 4.0 |
fix physics-error about metal thermocouples. The seebeck voltage comes from metal wires, not from the couple
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| Jan 21, 2021 at 2:36 | comment | added | wbeaty | @horta (old comnt) Good point: the Seebeck/Peltier effects in metals will mostly involve the temp-gradient appearing along the wire, while the metal-metal work-function doesn't change much. Semiconductors behave quite differently, with temp. altering the pn junction's Volta potential. In all-metal TCs, the "thermovoltage" originates in the hot/cold gradient of each wire, while for TC devices based on silicon, it comes from the junction. (Heh, it's like solar cells and LEDs based on phonons rather than photons. "Dark-Emitting LEDs" are when we view a Peltier cooler using a thermal cam!) | |
| Jan 21, 2021 at 2:23 | history | edited | wbeaty | CC BY-SA 4.0 |
add WP links
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| Aug 16, 2017 at 22:27 | comment | added | horta | Why does the voltage change with temperature? Separately, this description is drastically different than how the Seebeck effect is described in various places. I'm trying to noodle on whether one description is wrong or it's two completely different ways to describe the same macro effect with both still being valid. Thoughts? | |
| Feb 20, 2017 at 8:14 | comment | added | Ale..chenski | That's the issue. 99% of educational materials omit this circumstance that two other metal-semiconductor junctions must be present in the actual electronic device. Then the distinction between rectifying Shottky junction and non-rectifying Ohmic contact gets lost, without any explanations how the "heavy doping" (for making the contact "ohmic") is blended with presumably "normal" doping levels at the p-n junction. All this makes all web-based pictures of zero-biased diodes brutally misleading, starting with Wikipedia. | |
| Feb 17, 2017 at 23:30 | comment | added | wbeaty | When the metal terminals are connected to the silicon, one junction charges to ~+0.35V, the other to ~-0.35V. These exactly cancel the PN junction-potential (so if the leads are touched together, zero picoamps.) A PN diode is like one PN junction plus two Shottky metal/silicon junctions in series. Yes, an eletrometer-voltmeter should detect the 0.7V 'charge' on large silicon pieces. Make an insulated Faraday Cup, connect electrometer to the cup and to earth. Briefly stick a charged object into the cup and observe electrometer reading. Or just measure mV with a field-mill instead. | |
| Feb 17, 2017 at 22:48 | comment | added | Ale..chenski | "What if we bump a slab of p-type silicon against a slab of n-type silicon? That's a self-charging capacitor, and it produces roughly 0.7V between the silicon slabs." This statement implies that any off-shelf silicon diode would produce 0.7V standalone, if measured say, with a hi-impedance voltmeter. This doesn't sound right. | |
| Feb 17, 2017 at 5:52 | comment | added | mbrig | Excellent answer, wish my profs started with something like this instead of just math! | |
| Feb 16, 2017 at 17:56 | vote | accept | Mr.Robot | ||
| Feb 16, 2017 at 10:18 | history | edited | wbeaty | CC BY-SA 3.0 |
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| Feb 16, 2017 at 10:12 | history | edited | wbeaty | CC BY-SA 3.0 |
ps, bandgap
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| Feb 16, 2017 at 10:01 | history | edited | wbeaty | CC BY-SA 3.0 |
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| Feb 16, 2017 at 9:54 | history | edited | wbeaty | CC BY-SA 3.0 |
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| Feb 16, 2017 at 9:42 | history | edited | wbeaty | CC BY-SA 3.0 |
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| Feb 16, 2017 at 9:35 | history | edited | wbeaty | CC BY-SA 3.0 |
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| Feb 16, 2017 at 9:22 | history | answered | wbeaty | CC BY-SA 3.0 |