How does a reverse biased diode work at the molecular level? - Part 3 | Intermediate Electronics

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Table of Contents:
0:00 Introduction
0:15 Difference between forward bias and reverse bias
0:37 How the voltage pulls the carriers away from the depletion region
0:58 Why the depletion region widens under reverse bias
1:06 Energy band diagram of a reverse biased diode
1:54 Breakdown voltage and the avalanche effect
2:47 Summary

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[architchhajed]

Thank you so much sir! I was very confused as to how a current would flow in reverse biased condition. But your videos and energy level diagrams along with animation really made me understand what actually happens and what causes the current at breakdown voltage to be really high. Thank you so much.

[lokeshmishra]

this was the most amazing video i have even seen, , I just wish he explains the VI characteristics too

[stefano.a]

In the animation it would be useful to represent the electrons, from the left conductor, passing through the p zone in the valence band, until they reach che depletion region increasing it thickness

[Omkharche]

Woh!
just cleared the confusion in such a great way!!!
And your presentation skills are top notch professor!!!!
Thanks

[kanneboinavenkat]

How do you made animations? Explanation with animation is really excellent. I want to learn to make these kind of animation for different concepts. Can you please tell me how did you do that? Thank you.

[divinermiraculer]

Please what is a breakdown current? I want your definition, you're a great teacher.

[shaktigg]

why electrons are not crossing from p type to n type ?

[arturaras]

thank you very much for your effort. But to me i still finde some questions which are not allow me to understand it fully:

1:09
In reversed biased mode the conduction band has in general no electrons left. According to your picture there would be a possibility to flow from the p-conduction band to the n-conduction band. Only electrons which are thermaly generated from the valence band exists there, and they are the reason for re reversed diode current. Am i correct?

Same picture:
Actually all Explanations say that there are no wholes left in de p - valence band, so there are no current carriers left. But actually there are electrons filling the wholes. And they are still electrons which still can produce a current. I can try to press more and more ectrons into the p-valence band. So I can increase the potential of the Electrons until they have enough energy to overcome the depletion region.

Am i also correct?

[leazamansky]

Thank you so much !!! your videos have cleared many confusion.
I would love if you could explain about photodiodes, like how they work and how they are different from regular diodes :D
Again, thank you!!!

[firstlast]

Here's what I don't understand about reverse bias. It says "holes move towards the left side because they are attracted by the negative voltage." But there is no such thing as holes moving. The only way a hole moves is if an electron is moving in the opposite direction. It's all electrons moving. So now the question is, exactly which electrons are moving? Are electrons from the voltage source, maybe a battery, moving into the P side, combining with the holes, making it look like holes are moving to the left into the battery? Or is it electrons in the P material itself moving towards the junction, making it look like holes are moving away from the junction? Also, if it is electrons in the P side moving to the junction, then why don't they cross the junction and go into the N side? Why do they stop once they hit the junction, or maybe they stop a few atoms away from the junction, since the atoms right next to the junction don't have any holes for the electrons to join with.

All I can think of is that it requires a small amount of energy to get the electrons in the P side to move from hole to hole towards the junction, but then the electron, once it's in a hole, does not want to leave that hole and jump into empty space, where the N side is. There are no holes in the N side for the electron to jump into, so they stay put in the P side. Unless you apply the breakdown voltage, and that is so much energy that it does force those electrons to jump into empty space in the N side, and current flows in the reverse direction.

[Vineger]

Great video and it explained almost everything, but i am still confused about 1 thing. At 0:52 why electrons move to holes(near depletion region) and get fixed there? Why those electrons just do not go through depletion region and then further?(intuitively battery's positive terminal attracts electrons more than depletion region repels them, therefore they should move forward right?)

[doku_domu]

When the electrons move from the N-region to the P-region do the electrons first go to the conduction band of the P-region and then lose energy (heat or light) and go to the valence band of the P-region?
I would appreciate if u could answer this question fast as im working on a project

[lightyagami]

Why does the positive terminal of battery attract s elctrons. Isn't the positve terminal and the negative terminal of battery just a convention. And what about the current which battery supplies to diode. Where is that?
Plz answer

[suchethagara]

Literally YouTube is place of wisdom for the younger generation, as usual awesome video and explanation ❤

[MS-oyvo]

Amazing short and concise video. These videos will steadily increase in view count for eternity!

[RazaKhan-nlgg]

So will a diode show some potential drop which is equal to the breakdownvoltage like 0.7 volt in forward biasing and the current here passes by breaking simple covalent bonds by high energy and attract them into the conduction band but how the current passed in that depletion region in forward biasing?

[유지태-ls]

if I google, I find reverse bias diagram and it's p type fermi level is higher than n type fermi level. Does this mean the voltage is higher than break voltage?

I think only forward bias will have current. Then why fermi level difference doesn't make current in reverse bias?
(fermi level is energy level at which 50% of electrons are in at 0K as my knowledge. It's hard to understand for me)

[atexnik]

1:15 you probably meant the opposite; free electrons can't go up, and holes can't go down, because the free electrons are in N region, not P. This is how you tought us in previous videos.

[prabhatmishra]

I will share your channel with my friends

[theodorejackson]

I love the completeness that the CircuitBread videos offer. Very intuitive. Very comprehensible. What I don't understand about reverse bias is this: The high concentration of majority charge carriers is the driving force responsible for diffusion (hence the name being analogous to diffusion from high concentration to low in liquids). Yet reverse bias reduces those high concentrations, which would seem to reduce the force propelling diffusion and thus reduce the depletion voltage. But it increases the depletion voltage. This seems counter-intuitive. Can someone help me visualize that?