Timeline for When an electron moves in the valence band, does it need energy?
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22 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jun 10, 2023 at 14:24 | comment | added | my2cts | @VVidyan This is not electron but hole conduction. | |
| Jun 10, 2023 at 5:57 | comment | added | VVidyan | @my2cts So just to be clear, electrons CAN move between atoms to get into another bond while being in the valence band? I was of the (perhaps wrong) opinion that an electron could only move if it was in the conduction band, even if it was to go to another bond. | |
| Jun 8, 2023 at 22:50 | comment | added | my2cts | @vvidyan No electron is activated from valence to conduction. The electron is just moving from one bond to the next. | |
| Jun 8, 2023 at 5:50 | comment | added | VVidyan | @my2cts While the total energy remains the same, such that no net energy transfer from the environment is needed for valence electrons to move, will some 'activation energy' not be needed for the covalent bond to break? I visualised this as electrons temporarily jumping to the conduction band, moving (such that the hole moves) to another location and dropping back down. The net energy transfer is still zero, but some sort of activation energy is required. Is this a wrong thought process? | |
| Jan 28, 2021 at 11:39 | comment | added | Alchimista | @my2cts I've spoken of hopping because it seems the picture that OP had in mind. And your answer did not account for that. But I see that meantime s/he likely got a clearer picture, at least judging from the comments belonging to the original question. And I did not say that what you have wrote is wrong. Let me repeat: I took the question to be about the motion of carriers within the lattice and not about the carriers existence. Perhaps I should have commented to OP asking to make it clearer. | |
| Jan 28, 2021 at 11:11 | comment | added | my2cts | @Alchimista I was also being tolerant so far. Your comments are besides the point here and create confusion. Please submit your own answer and see what happens in the comment section there. | |
| Jan 28, 2021 at 11:09 | comment | added | Alchimista | @my2cts :( I was tolerant to the picture given. Do not reverse my comments. | |
| Jan 28, 2021 at 11:07 | comment | added | my2cts | @Alchimista You overshot yourself by bringing up hopping. Why? There is no hopping in a crystalline semiconductor at room temperature. Nor in a normal metal. Are you talking about very poor conductors of amorphous semiconductors? See en.wikipedia.org/wiki/Variable-range_hopping And what do you mean that "covalent bonds" "are not the holes / or the electrons" ? Covalent bonds are commonly and reasonably thought of as doubly occupied hybridized atomic orbitals. No electrons no bonds I would say. | |
| Jan 28, 2021 at 10:54 | comment | added | Alchimista | @my2cts don't overshot. Of course there a covalent bonds in a Sil crystal. But those define the lattice and are not the holes / or the electrons. Then there might be a hopping type of description. In that case the energy needed to leave the localized orbitals would be furnished by occupying another one. In that case conductivity should be at least thermally assisted. | |
| Jan 28, 2021 at 10:47 | comment | added | my2cts | @Alchimista "The band extends in the material" A band is nothing but an E-k relation for electrons in a crystal. What you probably mean is that the electrons reside in crystal orbitals. Note that for a full band, the Slater determinant of doubly occupied orbitals can be written in terms of localised, Wannier, orbitals and delocalised, crystal, orbitals. These are mathematically identical. That does not mean that there are no covalent bonds in a semiconductor like Si. | |
| Jan 28, 2021 at 9:31 | comment | added | Alchimista | @user394334 your description sounds like there is hopping. While one can account for your picture and say that what is spent in a site is recovered from another one, that is not the right picture. The band extends in the material. Similar in metals. There is no a shift of bonds. The free electrons are the bond. | |
| Jan 27, 2021 at 22:35 | comment | added | user394334 | @my2cts Ok, thanks. | |
| Jan 27, 2021 at 22:28 | comment | added | my2cts | @user394334 That is indeed the question I answered. If you like, you get the energy to break one bond from reconnecting the other. You always have one broken bond of you have one valence hole. | |
| Jan 27, 2021 at 20:30 | comment | added | user394334 | Now I am a little confused here. I will repeat my question if that makes it clearer: When an we have "hole conduction" in the p type in a semi conductor(I am not looking at the depletion layer, but the rest of the p type), when the holes then move the corresponding electron moves, and do we have to "break the covalent bond" these electrons are in, and then form new covalent bonds as the electron(hole) moves? If so, where do we get the energy to break the original covalent bond? | |
| Jan 27, 2021 at 19:21 | comment | added | my2cts | @Alchimista I don't see a connection between your comments and the question, hence my comment. | |
| Jan 27, 2021 at 12:25 | comment | added | Alchimista | @my2cts that is a strange comment. Can I say that that the OP question might ask for something else? OP can be even lead astray for all that I know. What had to do the presence of holes or free electrons with their moving? Either the OP means motion as current, that needs energy ; or promotion of electrons into a level /band, and that needs energy too. When you do not need energy to even have carriers, the only concept of "moving" is that of current. | |
| Jan 27, 2021 at 11:18 | comment | added | user394334 | @my2cts I see, thank you. | |
| Jan 27, 2021 at 11:15 | comment | added | my2cts | @Alchimsta If you have a question yourself feel free to ask it. | |
| Jan 27, 2021 at 10:40 | comment | added | Alchimista | Isn't that something moving need energy to be accelerated? I am afraid your answer is not to the question, as for I takes "moves" as current. | |
| Jan 27, 2021 at 10:23 | comment | added | my2cts | @user394334 No energy is needed as the total energy is independent of where the hole is located. | |
| Jan 27, 2021 at 10:08 | comment | added | user394334 | Thank you for your answer. What I am wondering is in relation to your first paragraph. When we have hole conduction, do we then need to excite the electron to move? When a hole moves does the corresponding electron first get excited, then move, and then fall down to the valence band again? | |
| Jan 27, 2021 at 10:03 | history | answered | my2cts | CC BY-SA 4.0 |