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I have a question about the reverse bias pn junction, while applying reverse voltage the material is being exposed to a reverse field results from the battery and we assume that this field is at the depletion Width only at the beginning before any increasing in the depletion Width this field is just added to the built in field, but as time goes on the depletion Width is getting wider and wider which means that the depletion Width increase,

My question is that the external battery field what is happening to it? The beginning of the process it was appearing as a separate physical entity and us superimposed on the original built-in field, but at the end of the process we consider the total Field due to the new charges in this region. I will provide a photo from Neamen

as in the picture the applied field appear then it disappears and the depletion Width gets wider

As you see the applied field that is above the charges Field it appears as a physical entity at the beginning of the process then it disappears and all what appear the new charges field , what happen to this applied field to disappear?

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  • \$\begingroup\$ @Neil_UK, its from Neamen semiconductor , i already wrote it in the question \$\endgroup\$ Commented Oct 18, 2024 at 13:03
  • \$\begingroup\$ The question makes no sense to me. In a particular, I am mystified by physical entities that disappear. A famous physicist once remarked that an answer was not even wrong. I suggest that this is not even a question. \$\endgroup\$ Commented Oct 18, 2024 at 15:47
  • \$\begingroup\$ I also can't really understand your writing, Abdelrahman_200. But it sounds a little bit to me that you are looking to understand what takes place in the pico- and nano- seconds after a switch is applied. That is a valid question because there is a very short period of time while things re-arrange themselves. Bearing in mind that a real device has three dimensions and has outside surfaces, which are also important, as well as the PN junction itself. If all of that's your question, it has escaped your wording here. If it is something else, I'm still missing the point. \$\endgroup\$ Commented Oct 18, 2024 at 23:13
  • \$\begingroup\$ @periblepsis,Imagine a situation there are two vectors one of them represent the charges electric field and the other represent the applied field and the net is their sum , as time progress the depletion Width is getting increased due to the more charges that filing the region so in order to have the net field the same the applied field vector must decrease in length, I abstracted the discussion on the vector representation, like the image provided in question the internal field is the charges field the external field above it , this applied field must at steady state disappear,how this done ? \$\endgroup\$ Commented Oct 18, 2024 at 23:23
  • \$\begingroup\$ @Abdelrahman_200 Please provide a source for the image. \$\endgroup\$ Commented Oct 21, 2024 at 17:38

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