Forward bias of semiconductor diodes?
Good morning,
I asked Microsoft Coilot if he could give me a summary of how the forward directions work.
Answer: – The positive pole is located at the p-doped region, the negative pole at the n-doped region.
– The electrons in the n-doped region are repelled by the negative pole and flow to the boundary layer.
– The positive holes in the p-doped region are attracted to the positive pole and flow to the interface.
– This makes the barrier layer smaller and allows electrons to flow through the diode.
– This enables the flow of current.
I'm not the best at physics (average B), but I think there's something wrong with the third bullet point. Because the holes are positively charged, and as we all know, opposites attract, I doubt they're attracted to the positive pole. Please enlighten me; maybe I'm making a mistake.
LG
(2 votes)
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This is a difficult explanation for the function. And actually I don’t understand them either. In fact, the holes migrate to the boundary layer for another reason.
I’d better deal with another one. All this is based on the fact that an infinite number of electrons are available at the negative pole as soon as the barrier layer voltage of 0.7V is exceeded for silicon diodes. The electrons are pressed in at the N pole and overcome the boundary layer in a flute manner. Then they fill the holes of the P layer. At the P Pol you can leave the diode and flow off to Plus. The remaining hole is free for a new electron AND moves to it until it is occupied. The thought model that it migrates to the boundary layer to pick up an Elekton at the boundary layer is wrong from my point of view. In a moment of recording that shows only all holes, but all move to the boundary layer. There was a good video I was looking for.
Thanks for the understandable answer! I just don’t understand how the holes, which are in the p-doped area, which is connected to the plus pole, are attracted by the plus pole and then still flow to the boundary layer
You still have to take into account the time aspect. At the beginning, in the industrial production process, foreign atoms are introduced into the silicon grid. On the one hand, atoms lacking an electron to be electronically neutral. So these are the atoms with the holes. They each have a positive charge. On the other hand, atoms are introduced that have an electron too much. Immediately after baking, haha, the barrier layer forms. There’s no tension! The diode itself has the voltage in itself because voltage can only be seen as a difference of charge carriers. That is, the holes are at the Pluspol because they were buried there. Not because they’ve evolved electrically.
See here
https://youtu.be/DDalmLJr2_c?si=BV-O9enx0gvps7HX
Yeah, that’s wrong. That would be two opposite directions. (Pluspol and boundary layer are opposed.
After the argument, one could say that the holes are also pushed away from the Pluspol and therefore migrate to the boundary layer.
Physically, however, it is somewhat different: the positions where holes can be are fixed. You can’t change. It can only be that a hole is occupied by an electron, then you can’t see it anymore. The electrons are attracted by the positive pole and jump from hole to hole. This then looks like the holes migrate from the plus pole to the boundary layer.
positive holes are not attracted by the +Pol, but also pushed away.
That’s what the AI is. She phantasizes too much and understands nothing. Take a book, there it is correct or research on the net, but not an AI…