How does a diode work - the PN Junction (with animation) | Intermediate Electronics
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- Опубликовано: 19 июн 2024
- To understand the definition of a diode you need to understand the...wait for it...PN Junction! We've gone over what semiconductors are in other videos but we finally start going over what you can use those semiconductor materials for. When semiconductors of different types are put next to each other, interesting things happen that can be used for a lot of different applications. In the most basic junction, the PN junction, a diode is formed. We lay the foundation of why a diode acts like it does when an n-doped material and a p-doped material are put together. It's crazy exciting stuff, because this is why you're able to watch this video on your phone. Seriously. Crazy, right?
For the transcript of this video with the animations embedded, check out the site: www.circuitbread.com/tutorial...
Table of Contents:
0:00 Introduction
0:43 The PN Junction
1:03 Formation of the Depletion Region
1:52 Barrier Potential
2:26 Energy Diagram of the PN Junction
3:33 Energy Diagram of the Depletion Region
4:22 Summary
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Although it's a 5 mins video but it explains a lot and what I mean by a lot doesn't just means "a lot" but it means A LOT! Thanks for the Exceptional work, and keep nourishing our minds with that great way of putting up science
1:06 1:13
I like your profile pic xD
Searching for animation and till now, this is the best available video on RUclips
Glad you liked it
Are u from fbise?
The question is why do course staff, who are paid for the job, fail to explain this concept as clearly and simply as this RUclips channel does!
Thank you for the video!
init
true true
on the course teachers' defense, they rly cannot explain the topics with the help of such intuitive animations shown in youtube videos
but still overall I feel youtube just does a better job at teaching us lol
You probably gave no indication that you didn't understand the material. It's adult learning, so if you don't get the most out of what you are paying for then that's on you. Secondly, there is a bit of confirmation bias in your statement. You have obviously received several hours of face to face tuition and have tried to read your course material in your own time, yet you give 100% of the credit to this video only? Do you think you would have understood everything about diodes if you had just watched this once?
@@TheEsky18 so true
after watching many videos, this series on transistor fundamentals is the best so far. The animation is clear and the speaker makes perfect sense. Subscribed.
This is the COMPLETE explanation.
Perfect. Good job!
amazing explanation that I've ever seen before. irreproachable scientific content. Well done!
This is the type of content that viewers seek from youtubers. Quality Content!!
The best video I find about diodes and pn junction. Learned a lot ❤️
I love the way you explain and animation, it's very easy to understand
Excellent. Clear and concise. Thank you.
I love this channel. Every time I feel my brain frying while studying I come here and understand it within minutes. Just excellent.
Great explanation! Thank You so much!!! Love from Brazil!
the best explanation, was looking for it for some time
Great video, explain a profound theory in a simple language
This was so helpful. I have my physics full syllabus grade 12 exam tomorrow and God semiconductors were one of the most confusing chapters...That is until I watched your videos
Thank you so much. The concept is crystal clear
Extra ordinary content. Thank you very much for sharing.
Great explanation, thanks for helping me to envisage it.
Excellent video and easy tounderstand, well done 👏
this is so helpful! thank God I found it haha more videos to come :)
Wow brilliant, thanks for this fantastic video, first time I actually understand how diodes actually work!
Awesome!
Finallly you helped me understanding this topic. Really thank you! Other websites make it so difficult.
You're welcome, I'm glad it helped!
beautiful English subtitle and animation video, thank you so much teacher .From Viet Nam with love
Its awesome.love from lahore ,pakistan.you are included in my list of best teachers.❤
great explanation! thank you
Very informative , thank you.
yes ,he is an inspiration for me ...thank you
Such a amazing video 😍 helpful
Great understandable explanation❤
Thank you for this clear explanation. Nam professor nim kaalu kelage thurbeku.
it is simply perfect I was reading slide almost 40 mins but couldn't understand anything about concept until watch this 5 minutes video.Thank you
Glad it helped!
Amazing channel :) thank u so much.
thank you. this animation helped me understand what my teacher couldn't through a powerpoint slide
great explanation
Great explanation....really !!!
Thanks so much man
High quality content 👍🏼
This is so far the best explanation for PN Junction for me
Awesome, great to hear!
Great video thank you
GREAT EXPLANATION
Thanks for the awesome animation and explanation! Wouldn't you say that the electrons that lose energy and recombine actually make up the depletion region? In your animation, the depletion region increases but the electrons in the valence band remain outside of it. Thanks for your answer!
Wow. This was so helpful. I wish you'd make a video on the applications of pn junction especial rectifiers
Your videos just make it so much easier to understand ❤
We do have a couple videos on diodes (which is just a PN junction) and I've been thinking about perhaps doing a small sub-series as part of our Circuits 101 series about the applications of BJTs (which are NPN or PNP junctions).Thanks for the feedback!
Thx sir, i would search across the internet for an easy explanation but for an 1h i could only find YOU
Why i didn't find this video earlier
U r doing great wrk
I appreciate it too much
Thanks for your feedback, we really appreciate it!
Thanks a lot ✅
It was helpful basic electronics tutorial I even seen
Thanks so much for the feedback!! Check out our site CircuitBread.com for all of our tutorials plus tools, an equation library, and more! 😎
too dope too good well done .
Thank you soo much
Excellent
Thanks. Love from India
even the concept which i didnt even had an idea in one hour explanation, i understood here after 5 minutes
Out of all the videos I’ve seen , this is by far the best ! Thank you so much sir 👍🏻
8076291502
Thank you thats help alot
this is gold
The best explanation for pn junction diode. Hey everyone, I wanted to praise CircuitBread for creating an incredibly helpful video. The content was so informative and well-explained. I'm sure it helped many others as well. Thank you for taking the time to share your knowledge and expertise!.
Thanks. Glad it helped!
Hi. Nice animation. Which software did you use to create it? Overall, nice video!
you are the best thnx
this video is heavily underrated
thank you
Thankkss really
I have exam after 1 hour
I read it in abook school
I understood superficially, but I didn't really understand exactly how it happened
Tq so much
Sir, thank you so much for making this video. It is extremely helpful and easy to understand! The textbook made me wish I would rather have my brains blown off😅😄😄😄
Well, I'm glad you didn't and that this helped!
superb explanation
Thanks!
thanks
How does the depletion layer get charge ?when n and p recombine,will there be charge
my uni cant explain this at all, have to come to your vids to properly understand it. Thanks
Happy to help!
waiting for the bread to pop out !!
Does active region and depletion region are same in LED? IF no what is the difference please explain
Thanks thanks thanks thanks thanks thanks thanks thanks thanks thanks thanks thanks thanks
That was very helpful 💕💕💕
You're welcome 😀
Nice work,,. Btw The free electrons diffusing through the depletion region from n region rapidly lose energy...
What makes them lose energy ?
Hi Roshan, my understanding is that the electron loses that energy in the process of overcoming the depletion region, which is acting as a barrier. In other words, it uses that energy just in the process of getting to the other side.
Hi, thanks for the interesting and instructive video, but one thing I don't understand is why we can't disconnect these semiconductors from each other.
Thank you!!
Thanks for the question! Do you mean, why we have to have the two different doping regions? If you have just a p-doped region or an n-doped region by themselves, they're just a piece of material that doesn't conduct particularly well. It's when they're put together that the magic (or science) really happens! If you're not familiar with the background on doping, I recommend starting at the beginning of our Semiconductor Basics playlist: ruclips.net/p/PLfYdTiQCV_p7sDswtLZKK43BWOd2mTmHC
@@CircuitBread Thank you for the answer, I will definitely start watching.
I worded my question incorrectly.
I just can't understand the Seebeck effect.
How does it happen?
Hello, I'm a bit confused by the animation. when the free electrons go over to the p-site, you would think that the result would be a neutral charged atom at the N-site, but instead it becomes a positive charged hole?
I guess it is because it are mostly neutral molecules from the n-site that will lose an electron?
Why is the Valenzband empty? dont we need to fill lower states with electrons first ?
after pentavalent doping the extra electrons goes in conduction band of that semiconductor am i correct?
i understood everything and clear my doubts thanks!
Yep! Excellent to hear. We do have some other tutorials on doping if necessary but it sounds like you're good to go!
Finally understandable english!
First, let me thank you for the good videos. But in this one, I wonder if it's factually correct. What I have in mind specifically is the energy diagrams at 2:30. There is not enough space to explain in detail but in a nutshell: the valence band of the p-region can be above or below of valence band of the n-region, depending on used materials. Take for example P atom with electron configuration [Ne]3s^2 3p^2 => 5 electrons with principal quantum number = 3 vs B atom (you named it as p-type impurity) with [He] 2s^2 2p^1 => 3 electrons with PQN=2. So electrons in the B valence shell have even lower energy than those in P. Ga or In atoms would work (see periodic table).
Second and more importantly - when elections recombine on PN junctions the electron energy needed to escape from P atom DOES NOT change. Bands are not moving anywhere contrary to your statement in 3:41. These are still the same atoms. P atoms further in the n-region are willing to give up the extra electron same as before. These may either recombine with holes in the p-region closer to the PN junction (causing hole current) or may try to penetrate to n-region and recombine with the n-region hole.
The only problem is really that there is already a barrier of earlier recombined negative ions of B/Ga/In atoms. These exert a repelling force on free electrons coming from the n-region according to Culomb's law (as you correctly explain in 2:00).
In a nutshell to understand PN junction it's critical to understand 2 distinct forces - 1) Culomb's law and 2) the proclivity of electrons to fill the atom valence shell in some patterns which is key for understanding chemical bondings, the periodic table, and chemical element properties.
Also, I think there is no conduction band but rather conduction space simply for all electrons with enough energy to escape the atoms. So there is always a "conduction band" overlap and an electron excited enough can always go anywhere (you only need to heat things up enough). And of course, energy comes in quantum so the conduction space is not actually continual but discrete, but it's possibly not important here.
At least that's how I understand it, which also may or may not be correct. :)
which app did you use for these videos?
Hi Ayca! Our videos guys use the Adobe Suite for video editing. I think it's Premiere for the video editing itself and Aftereffects for the animations.
We hope this video was helpful! We have a couple more videos on how diodes/PN junctions work when forward and reverse biased, we recommend you go check them out as well. We also have a wide variety of other tutorials on semiconductors, so explore our channel if you have any more questions on this topic. If helpful, we have the transcript for this video on our website here: www.circuitbread.com/tutorials/how-does-a-diode-work-part-1-the-pn-junction Take care!
can we refer to this type of attraction (electrostatic) between positive charges and negative charges (ions) as an ionic bond attraction or ionic bond is different from this case?
No, they're not an ionic bond, and it's not really an attraction, more just varying energy levels and things naturally wanting to drop energy levels by falling back into a hole. Hopefully that helps!
Why the energy of conduction band and valance band in n type semiconductor is slightly lower than those in p type conductor
can you explain reverse recovery some time
Hi, love your video and the clarity of your explanation. However I'm quite confused as to why the valence band of N type also loses energy, when only the electrons from conductive band cross over to the P type. Shouldn't in that case only the conductive band in N type lose its energy, while the valence band stays the same ?
Hi Tomas, I'm not quite sure I understand the question. I think you're asking why, when two materials meet together, both the conduction AND valence bands move when only the electrons cross over to the p-type? The distance between the bands is set and won't change, they will always shift together and never move closer or farther apart. However, I don't feel like that is really your question. Could you clarify the question please?
@@CircuitBread That is exactly the question I was wondering about, thank you :)
you forgot to mention that the holes from the p type semiconductor diffuse to the N type semiconductor the same mechanism as the electrons diffuse towards the p type semiconductor.
but overall video is amazing, thank you.
Very true, thanks for the feedback!
Can you kindly explain the reason why p side energy levels are made higher and in n-side they are made lower. Also why in the state of equilibrium holes and electron Fermi level align at same position in order to achieve equilibrium. Also as holes and electron which flow are actually in bond with the atom, so hows does when they are in contact, what provides them energy that electrons move and fill the vacant charges in p side leaving a hole or vacant side in n side.. In many texts i have seen (but still confused) that they say, electron are near conduction band so as electron moves they actually decreases the amount of Fermi level in n side due to vacancy and increases the Fermi level o p side... but the logic that Fermi level will align finally for both p and n side, i am unsatisfied with it...Some says as depletion region is formed so why further movement of electron and holes do not occur that electron may go to conduction band of p region. Sorry a bit long query and may be dumb question, but please do clarify this and hope you reply to me. Also you said that electron coming from n type to p type during diffusion will fall back to valance band of p region. How can you represent this situation in a pn semiconductor. is it that the electron recombine with the immobile ion created in p region or what.
Why when the depletion area expands, the energy level of conduction and valence decreases in n region, "energy level or energy band of solid should be constant"
I have one question , does the electron only move to p region ? because I heard and read that holes move to n region , i'm a bit confused.
Electrons and holes move around in both regions. The only difference is that there are more holes in the p-region and more electrons in the n-region. Things like to equalize, so as long as there aren't any external forces, electrons will diffuse into areas with more holes and holes will diffuse into areas with more electrons - this is diffusion current. Things are complicated by the fact that there are additional forces, both active and inherent in PN junctions, that oppose this motion.
Cool video, great video, and audio. How did you make the diagrams?
Thanks! All of the images and animation were done in Adobe After Effects. We almost entirely use the Adobe Suite as there's better overlap between the designers and the video team for our client work.
@@CircuitBread interesting, thanks for the response! It would be interesting for you to do a video on your audio and video setup. I am also curious what lave mic and camera you use. It looks and sounds professional.
It's pretty simple - we have some really nice Sennheiser wireless lavs because we wanted them to integrate with the video setups we use for our client videos. But the cameras are actually very simple, they're Panasonic G7s. Since they're dedicated to the CircuitBread setup which has decent lighting and no movement, we didn't need anything too fancy for that. And I am not the video guy so everything I know is just from watching the team work but it seems like lighting and setup is more important than what camera you have. As I recently moved, we're rebuilding the CircuitBread spaces in my new basement, it may be fun to have a quick tour when we're done. We'll see!
@@CircuitBread thanks for the reply! Awesome that does seem like a good setup. I may try and replicate it for some videos I plan to make. It is actually hard had to decide what mic and camera to use so I appreciate the feedback. Green screen, lighting seems more straightforward but like you said also importat. Do you write a script and read it from a teleprompter? I subscribed and hit the bell so if you make the video of your setup I will definitely watch it! If you link the camera and mic to amazon as an affiliate you will also likely make some extra money.
Green screen lighting is surprisingly tricky, though it's not as bad if it's just me and there's not a table involved - we always have to be aware of spill. Speaking of, any videos in front of a green screen are done with a script and teleprompter. Anything done at the desk is outlined and then ad-libbed, which is why there's a higher amount of rambling, mistakes, and misspoken words with those 😬
We've talked about doing affiliate linking but are trying some other methods of monetization. We have some really cool ideas that we're pursuing that we think will allow us more time to create legitimately useful content without becoming shills. So far, potential partners have been very positive but we've only been actively pursuing this for a few months so we're not sure how well it'll actually work out!
So, when does the depletion region starts, when p and n are attach together or when voltage is applied?
A depletion region naturally forms as soon as they're "attached" together but then it gets wider when there is a reverse voltage. And shrinks when they're forward biased. Hope that helps!
@@CircuitBread Yeah it helps, thanks
Sir I did not get the points 2:43 can you explain for me ?
sir, Could you expain why PN is called minority device? And how MCLT affect device. Thanks a lot~
Sir, My Second Question is why does the free electrons rapidly lose energy while falling into the holes right after crossing the p-n junction (at 3:26) (I understand WHY it should, because the acceptor energy level is lower than the valence Band obviously, I just don't know what underlying phenomenon makes the electrons lose energy)
And, my 3rd Question is- similarly, what makes the overall energy level of the n region to decrease as soon as a depletion region is created? (at 3:39)
Your second question seems nearly philosophical when I read it. They lose energy because they tend toward the lowest energy level, just like why a marble in a bowl wants to settle in the bottom. And hitting the bottom of the bowl causes the marble to jump up, just like the insertion of energy (in terms of heat or light) causes the electrons to jump out of the valence band. Any underlying "why" below that... I don't know!
Let's see if I can do an adequate job explaining the third question. Even though the overall semiconductor has the same energy, the energy has been redistributed by the movement of electrons and holes within the semiconductor. As the n region is dropping in energy, the p region is increasing in energy, so that's where you get the balancing. And it isn't decreasing as soon as the depletion region is created, it's dropping in conjunction with the depletion region being created. The two things are related. Hopefully that clarifies things!
Thank you so much, all your answers are really helpful. But I'm so sorry that I'm having too many questions to bother you again and again, ha ha!
Anyways, so what you just said about why electrons lose energy while falling into holes (you said that it's just a natural tendency to
have lowest energy) so why does that tendency come visible "after" the electron has crossed the junction? Does it mean that any valence band electron on the n side can just jump down to valence band randomly? If not, then what's making that change of energy drop ONLY after the passing of electrons? (it's fine if you can't give the accurate answer to this, I went pretty deep😅...but if you know any other resource as suggestion where I can find the best but easy explanation, that would be a great bonus favor, too)
For your response to the 3rd question (energy gradient increment between n and p regions with depletion layer formation): I do want to ask that referring to one point you made in the video about why initially the energy levels of n type semiconductor is naturally a bit less than p type. There you had explained the reason in terms of effect by nuclear attractions. So my question is, if we consider the energy drop / energy jump in the respective n and p regions during the depletion layer is being formed, how can that be explained in terms of thr nuclear attractions (individually for n type and p type)?
@@aryanandaleebazim823 No problem! My only concern is that we're getting close to the edge of my understanding -and I'd prefer to have Dr. Campbell help (a professor and awesome person that we've used as a resource to double-check our work in microelectronics) but she's always crazy busy. So I will do my best!
I think we need to expand the bowl analogy more. In reality, it's not just one bowl, it's trillions and quadrillions of bowls per square centimeter of lattice. And even though that may sound like a lot, it's absolutely tiny compared to the amount of atoms in that same area. So, at this point it becomes a statistical thing. But the more bowls there are, the more likely that an electron will find one and then fall into it to the lower energy level. Once the electrons cross through the depletion region, there are a lot more bowls, so it's statistically much more likely that the electrons will drop down in energy level at that point.
If I'm understanding this question properly (which I may not be) you're trying to figure out why the n and p regions have an even greater difference in energy levels due to the nuclear forces on trivalent versus pentavalent electrons, AFTER the depletion has been formed. I think, in this case, that this is not actually the case. This change after the formation of the depletion layer is not due to the nuclear forces between the nucleus and the valence electrons but simply by the energy of the extra electrons that are moving from the n region to the p region. So, instead of the inherent differences in energy levels due to the nuclear forces between the nuclei and electrons, it's due to the physical movement of particles that have intrinsic energy. Does that make sense? I'm not sure if I could go any deeper than that without getting a degree in chemistry or physics. 😀
Best video👍
Thanks for the feedback!
@@CircuitBread I'm waiting for videos: forward bias, reverse bias
@@chuaca8545 The forward bias video is up! Working on the reverse bias video now. Thanks!
@@CircuitBread It's so helpful for me
can you post a video in which you explain the solar cell working principle, please.
Oh, that would be a good one! We have the next 6-8 months of content already roughly sketched out, but we're hoping to get Josh a little bit of help soon, if so, hopefully we'll have a bit more bandwidth and we'll try to fit this one in. Thanks for the feedback!
Excellent. Am waiting for your valuable courses. You're just doing great !
nice video but at 1:11 electorns filling the holes shown as they stay as negative charges. As I read in a book , they neurtalize each other and some majority carriers holes and electrons are lost in this process. How negative charges exist in is because holes leave behind electrons when they diffuse throught, similar to electrons leaving out holes behind them.
Yep, you're exactly right - those electrons combine with the holes and while the electrons still technically exist, they're no longer important to consider as they're now tightly bound to a nucleus and there is no net charge. This is the tradeoff in trying to show a process visually that can't truly be shown visually in a realistic manner. If we'd made the hole and electron disappear, that could have been confusing in that people would have thought the electron literally disappeared, when it's really just the charges are canceling each other out. So we had to make a decision on how we thought it best to represent it. But it sounds to me like you have a great understanding of the topic, which is great!
@@CircuitBread thank you for the reply and also great videos !
Depletion layer has No charge then why u asign it by + & - charge
oh my god
good englis !
Why dont the electrons in the n-type move into their the depletion zone from their side ? they have a sea of positive charges to the left and a sea of negative charges to the right. I get why they dont cross they boundary this makes sense to require some energy , but why dont they just move into the depletion zone. I understand that there is an electrostatic field that points to the left but i dont understand why this works out when i imagine an electron that is near the edge of the depletion region from the right , naturally the forces would push it into the depletion region
wow
Hello sir I'm big fan 🙏
Thanks Utkarsh!
"the trivalent atom has lower force in the talk is wrong. the Born nucler core has strong force becuase the out layer electron is more close to the core.
so a diode allows current to pass through when activated Like a gate. so why wouldnt use a mosfat instead because a mosfat also allows current to go through when activated.