Timeline for Do the recombination of charge carriers cause the diode to stop conducting?
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| Jun 18, 2013 at 0:46 | comment | added | midnightBlue | No but making the base longer increases the effect of the excess charge carriers since they have enough time for a high proportion to recombine with the majority carriers. This process causes delay since when you switch off the diode, they have to "come back" again to restore charge neutrality in their original majority side. (As how I understand it, I'm still learning) | |
| Jun 16, 2013 at 15:23 | comment | added | The Photon |
In the wide base limit, all the excess charge occurs within a couple of L_p (diffusion length)'s of the depletion region. Making the base "even longer" doesn't add to the excess charge.
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| Jun 16, 2013 at 15:21 | comment | added | midnightBlue | Hmm but for a diode to go from forward to OFF, all the stored charge on either side needs to go down to zero, so the longer the diode is, the more the charge (excess charge carriers recombined) that gets stored. | |
| Jun 16, 2013 at 13:53 | comment | added | The Photon | If you increase the length beyond the minimum for a "wide base" diode, I don't think it changes the analysis. The charge sloshing back and forth, IIRC, is more to do with the depletion region. | |
| Jun 16, 2013 at 6:08 | comment | added | midnightBlue | Yeah I agree with that! But what I meant was, if I arbritarily increase the length, will it matter? I researched here and there and I think what changes is the amount of charge you have to slosh back and forth each time you switch a diode. i.e. Delay. | |
| Jun 16, 2013 at 5:21 | comment | added | The Photon | I think (but my memory isn't perfect) that short base means that injected carrier recombination isn't significant --- essentially all of the minority carriers make it to the contact surface...so that pretty much makes your question not apply... | |
| Jun 16, 2013 at 5:16 | comment | added | midnightBlue | Cheers for that! So, is there any external difference in terms of external characteristics if a diode is long or short? (i.e. how do you tell without knowing its length) Does the length matter? | |
| Jun 16, 2013 at 1:27 | comment | added | The Photon | Another site with some explanation: nptel.iitm.ac.in/courses/Webcourse-contents/IIT-Delhi/… For your question, see the area around eqn 39 or so. | |
| Jun 16, 2013 at 1:12 | history | undeleted | The Photon | ||
| Jun 16, 2013 at 1:11 | history | edited | The Photon | CC BY-SA 3.0 |
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| Jun 16, 2013 at 1:08 | history | deleted | The Photon | ||
| Jun 16, 2013 at 1:03 | history | answered | The Photon | CC BY-SA 3.0 |