The PN junction | Class 12 (India) | Physics | Khan Academy

In this video, let's explore the famous PN junction. We will see what happens when we have a single crystal with a P-type semiconductor on one side and an N-type on the other.
Learn the next topic here --www.khanacademy.org/science/i...
Class 12 Semiconductors: We cannot imagine our life without computers today. But what makes a computer tick? What's making this technology grow at such an exponential rate? It's all due to semiconductors. As unbelievable as that might sound, altering the properties of semiconductors allows us to build these computers. In this topic, we will explore the world of semiconductors. It's a journey from what semiconductors are all the way to creating building blocks of these computers.
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Created by Mahesh Shenoy

[@naomiemredha866]

OH MY GOODNESS, THIS WAS INSANELY GOOD. BEST PN JUNCTION VIDEO ON THE INTERNET

[@360wheelz5]

Indeed. After recombination, the immobile charged ions are left behind which set up the barrier potential. I couldn't understand what it was that set the barrier but now I know!

[@Mahesh_Shenoy]

You know, while I was making the video, this was the reaction I hoped for. Thanks for making it true!

[@siddharthamondal4346]

@@Mahesh_Shenoy Awesome video sir.

[@blueblood-_-]

Exactly This is has to be the best video . Explained so nicely , even the smallest doubt was cleared. Amazing

[@suryanshkhatri7929]

Agreed, 4 years after it was made, and 2 years after this comment was written, it's still the best video

[@jessiondiwangan2591]

I spent my whole year looking for this kind of teaching, finally i found ya

[@singshokeen6514]

Agree

[@avikbrahma4691]

Same for me too

[@arthureaton8]

Goodness! I've been an electronic engineer for more years than I care to admit. On occasion, I still like to review the fundamentals to keep my knowledge fresh, so I've heard the P-N junction story many many times. But I have to say, this was the best explanation I've ever come across, and even after all these years practising engineering, this little video has greatly improved my understanding of this very fundamental concept.

[@Parapresdokian]

2:09 I always love humour mixed with spontaneity. Mahesh should start his own patreon. I sooo badly don't want this man to quit his job for monetory reasons.

[@dhurbarajpuree2992]

3 times I rewatched.... It's a gem video.

[@Angel-ud9jm]

Awesome way of teaching.its the best video I have seen in KZbin that explains about pn junctions,diodes..... I really appreciate you👏👏👏

[@esphilee]

I have watched no less than 6 videos. This video is one that makes sense. The rest are like my school teachers, they just brush things under the carpet and call it a day. Well done.

[@s.3421]

Guys I bet uh, u won't get a better video than this in the whole of the utube!! I wasted a lot of time, searching for a video where I could understand p n junction clearly... And then I found these videos where I understood it finally!!! Tqsm🙏🏻🙏🏻👏🏻👌🏻🥳🥳

[@user-yj9qf3vu6u]

I m in love wd this topic now , no crammed concept , just pure physics and physics . This is insane 😍

[@anonymous20060]

And little bit of chemistry 😊

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No Marvel no Dc. These videos introduces another universe.

[@Kyle_da_athlete]

Literally the only video on this topic that got me to understand this can't thank you enough

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[@freeverse4210]

Best thing Khan Academy (especially Khan academy india) did to me is that they developed intrest of physics and now I have such a fond to listen these lectures it gives my mind a massaging effect

[@carolinerozario9702]

You're the best sir!!! Just loved the explanation! You deserve more n more subscribers... on the other hand, unacademy n etc just advertise their platforms! But Khan Academy is so service oriented! Loved it! Thanks so much!!

[@wassupdee13]

Love his explanation and kindness to answer some of the key questions posted by others. They are very helpful. I appreciate it so much!

[@whomptilizes]

Absolutely amazing. You're the best!

[@lakshmishajahan8391]

This was very helpful! Thanks allot. I finally understand it!

[@brothercavil491]

At 7:17, why isn't the minority carrier electron from the P side not repelled by the negatively-charged Boron. I get that it's attracted to the positively charged Phosphorus, but it has to get past the Boron first...

[@bxbybxnny5640]

I think its just because its energetic enough

[@nareshsharma2003]

All your videos explained with such clarity, its the best way i gained knowledge... Loved it! Please keep making them ❤️

[@260eeeprasuna2]

You give a clear clarity on the concept.... Great 🤝🏻

[@riturajborah382]

Excellent explanation! Thanks a lot for such free amazing content! Regarding the PN junction, we could also look at it from the perspective of neutrality. Overall, the p-side and the n-side, both are neutral and they want to remain neutral. At the PN junction, naturally, the nearby electrons and holes will recombine, but only to an extent where the tendency to remain neutral will pull the charges from going further. For example, on the p side, when some holes are neutralized by the electrons from the n side, there will already be some net extra -ve charges on the p side. These charges will resist further charge migration towards the p side. The same for the n- side.

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Bestest video..I hav ever seen.. thank you very much...✌️✌️

[@armyarmyyeah.0727]

Thank you..I needed this badly

[@dakshinaak.s.5638]

BEST VIDEO AVAILABLE ON INTERNET FOR THE EXPLANATION OF MOTION OF CHARGES IN PN JUNCTION

[@rachitmehta7738]

This is just tooooooooo gooooddd . I was almost crying because this was hard to get, but this was amazing !!! THANK YOU

[@bholarajwar7022]

Amazing.....

[@catharperfect7036]

Took me a long time to find someone to explain this clearly.

[@harshitasharma4820]

i hour i spend on utube so that i can understAND THIS TOPIC BUT then i came to this video andd hasshhhhhhhhh.... i am able to understand everything thankuuu sooo much i was soo confused before but now i understand it very well

[@SuperSaltyFries]

Great video, thank you very much.

[@prachisharma1545]

That was so conceptual ❤

[@ramanjitkaur3124]

Justttt wowww❤

[@ramaswamy499]

If we see this video we can easily understand p-n junction best video thank you

[@arunavomondal9750]

The best teaching I have ever found... 🙂🙂🙂

[@user-zq4zt1qc3e]

what an explanation thank you very much

[@NiharikaAChirayil]

Thanks for the video it helped!

[@abdurrahmanfaiz6230]

I have a question. Why the electrons can't attract the holes but the negative ions in the depletion regional can attract the holes to the p side?

[@madivalappamakond4060]

Thank you sir for giving this beautiful lecture which I never understood when my teacher teach me

[@sadiaafrin4208]

The best lec I've ever seen on this topic😍😍😍

[@osamazahid715]

you did such a brilliant work!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[@anitajanu9638]

Realistic and enthusiastic explanation 😊😊

[@parthparmar6901]

Best pn junction explanation video

[@richardknipe2733]

Excellent teacher!

[@vidhyapriya4722]

thank you soo much !! gr8 work

[@OuranosGod]

Thank you man! I finally got it! ❤️

[@golamwahid8630]

Great!

[@jaredmusci5403]

Extremely helpful explanation! Watched so many videos and failed to understand the formation of the depletion layer, but this seemed to make sense so thank you. QUESTION: why can't the minority charge carriers from either side recombine with the majority charge carriers from that same side? In other words, why can't the minority electrons on the p-side diffuse into the majority holes on the p-side (or vice versa for n-side)? From a gas diffusion perspective, this makes sense since they stem from the same gas, but in reality electrons and holes are not actually gases. I assume it has something to do with the energy gap between the valence and conduction bands but am still a bit confused. If you see this, thank you.

[@s.h.1991]

You’re a life saver i swear

[@inanis6707]

I thought i knew this concept because I could spew out big words, but thank you so much. Marks do not mean you understood the concept

[@Priyanshu_Kumar_Pandey]

Thanku so much sir

[@ahmadeldesokey9844]

Beautiful mind

[@mohdkashif263]

Best video on youTube thnx so much

[@chicken3022]

If the minority charge carriers are crossing the depletion layer then don't they feel repulsion from the exposed charge carriers on the same side p or n side . Ex: If a hole (a minority charge carrier) , wants to reach p side from n side then the exposed +ve charge on n side won't repel the hole crossing the barrier?

[@KrrishNandrajog07]

Feel aagayaa 🔥

[@mariaacosta6771]

you are sooooo good!!

[@mpscscience7609]

Awesome explanation......

[@electronicdevices6496]

Awesome

[@kapilraj3129]

The best part is that it doesn't have ads

[@bns-xt6wf]

4:18 That would be extremely so bad... We worked so hard to get to this point? Right? That was so good

[@shaikrafik6300]

Amazing

[@fromexoplanet21]

Wow👏💖

[@LeviAckerman-kk2ie]

Super useful... Better if u explained how electron and hole destroyed each other 🤔

[@rijuwanahaque8054]

Thank you broh

[@todorpetkov6525]

a link for the previous video please

[@khamisfarid3804]

Anyone knows how those videos were made ?

[@abdulwajeed3479]

Damnnn good explaination!!!!

[@boltez6507]

Wait wont the minority charges(free electrons) in P tupe fill up the holes??

[@lakshminandhana2058]

Thank you so much sir

[@jahanvidixit9497]

U rock🔥🔥👏👏👍👍💥💥

[@anishatadkod1778]

I am speechless

[@harshavardhanhajeri1753]

Can we do hcv after this?

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Hey, great video...also u sound like kumail nanjiani :p

[@abhishekahirvar7783]

here is some high quality study material

[@xiaohanjiang4960]

Why do holes and positive charge repel?

[@abhinav1299]

Ahh so finnally my doubts are clear

[@vigneshreddyjulakanti7583]

The BEST

[@laibakhan3905]

Asslamalikum Sir! Why minority charge carriers don't diffuse with opposite charge to become neutral, like why holes in n region attracted by electrons to form neutral atoms?

[@aloomaloo1427]

Because opposite charges attract each other .

[@guuguu7559]

This is insanely underrated

[@tashithadilshan3738]

Super explonation

[@pranavkrizz1553]

I need to know how those animations were made🤯

[@jeanxza5395]

I don't understand why the rogue holes/free electrons don't just combine with their counterparts. Aren't holes just the absence of electrons in the covalent bond? So why would a rogue free electron in the sea of holes not immediately go and fill any hole it finds?

[@ourtamilnadu9011]

Sir,how diffusion causes charged zone in junction

[@Mrgook]

Finally........😊

[@ShawnDypxz]

At 5:48, I know that holes can't diffuse; it's the valence electrons which are moving. Now, my confusion is - are those valence electrons of the p-type or the n-type? If the free electrons can't make it to the p side due to the repulsion ( but there are some energetic ones), I don't think valence electrons of the n-type can contribute to the hole current because they have very much less energy level than the free ones. And what does it mean by energetic holes? Could you clarify this, please?

[@mobrienmagpie]

I have a similar issue with this, also it describes holes as being attracted to the negative ions, I don't think this is correct.

[@sereneantoleslie1754]

@Mark O’Brien Yes how can holes be attracted to negative charge? Bcuz Neutral bodies cannot be attracted to charged bodies. And holes are actually neutral..they are ONLY CONSIDERED as positively charged particle. Am I right?

[@niravsavla9993]

Just asking so at equilibrium n-side develops a -ve charge and vice versa for p-side?

[@KhanAcademyIndiaEnglish]

Yes. As you will see in the future videos, this is the reason there is potential difference generated.

[@vishank7]

Hello sir, I dont understand how the movement of minority charge carriers is aided. Let's say weve got an electron in the Pside, while going towards N(left to right), wont it face a wall of negatively charged atoms in the depletion region first? How doesnt that stop hinder the election's movement? Thank you already!

[@ajithettiarachi3650]

They are actually neutral due to their associated electrins

[@AarshWankar]

It doesn't, as an electron on the p side faces attaraction from the positive layer on the n side and repulsion from the negative layer of the p side, both of which are equal in magnitude. So the net force on an electron on the p side is zero. So it can randomly pass into the depletion layer after which it will get accelerated towards the n side due to repulsion from the left and attraction from the right.

[@zinethsrijayanath1483]

I can understand why both p n sides haven charges I think they are nutrul in before connecting them because Si P and B atoms are not changed. Then.

[@kakatiyaraju3378]

tq so much

[@martinstojanovski9106]

Can you help me with this Sir?In the P type,we have the negative Boron ions and we have holes just behind them.Why some of the electrons from the ions don't drifft to the holes and that way the holes and the electons will vanish in the P side?And how can holes be repeled by the positive phosporus ions?

[@KhanAcademyIndiaEnglish]

When Boron accepts electrons they leave behind a hole. This accepted electron is now covalently bonded with other carbon atoms. Secondly remember that motion of holes is basically valency electrons moving in the opposite direction. It's hard for electrons to move 'away' from positive phosphorus ions because they attract it. This in turn means it's hard for holes to move 'towards' the phosphorus ions

[@madhum8270]

Oh my god!!!! This is so amazing.😃

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[@madhum8270]

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[@AJ._7]

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[@ToHereCan]

During the movement of minority charge carriers, how can holes be attracted to the boron anions because I thought it was previously said that they are not actually positively charged particles themselves?

[@hannahsahasra8917]

The minority charge carriers here are not in a way attracted to the boron anions , it's the electric produced from n to p Makin them move and this is why the the minorty charge carriers in n type ie holes are sucked well not technically 😂 but yeah they r sucked into the n type and same goes with minority charge carriers in n type

[@techsinc]

Holes can attract electrons via Coulomb interaction. Otherwise, you would not have the built in field at the PN junction.

[@AshirbadHembram]

As you said majority Charge Carriers are Holes and Minority charge carrier are electrons and also Boron is negatively charged and again whole P Type crystal is neutral not able to understand this. Why these holes are not combing with minority charge Carrier itself while it is independent means not joined with another N type Crystal

[@Aradhikamahajan9892]

Why acceptor ions are negatively charged before diffusion

[@shekarcmmamdabad5748]

I have a doubt Sir . how can there be an electric field near junction (depletion layer) actually pentavalent element (P+) are separated very far from each other and same in case of B- so how can there be an electric field near junction

[@KhanAcademyIndiaEnglish]

Because atoms are very small In silicon we have about 10^22 atoms per cm cube. If the doping concentration is 1ppm, it means there are roughly 1 million atoms between 2 neighboring. That seems a like a lot but this means there are 10^22/10^6 = 10^16 dopant atoms per cm cube. That's still a lot isn't it?

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Once I heard that its not teaching but a students mind which make him topper but after watching this I realised that its teaching which makes a student mind topper.👍🏼👍🏼👍🏼

[@chaeonxxx6404]

Topper has another meaning. But learner

[@chaeonxxx6404]

It’s not about making a student topper man it’s about information and knowledge to apply in modern physics better than these technologies

[@bajikeisuke8358]

what does it meant by destroying each other

[@daniking5485]

bless u

[@ShawnDypxz]

Can someone answer this? @ 7:25 If free electrons from N-side can't make it to P side due to repulsion from negatively charged ions in the P side, how can minority electrons even move forward toward N side? Shouldn't the negatively charged ions repel the electrons from P side too? I know that they can be repelled forward but every time they move forward, there are always negatively charge on their way.

[@KhanAcademyIndiaEnglish]

You are right, guess could have used a better model. So in reality a minority carrier (like electrons in P type) don't wander around (as explained in the video). Since they have a high chance of combining with some majority carrier (like holes in P side), they would move very little before they recombine. However due to thermal generation another minority (and a majority) carrier will pop up somewhere randomly. So we can imagine these minority carriers popping up randomly, living for a short time and then disappearing. Since they pop up randomly. Sometimes they will pop up in the depletion region. This is when they get swept across due to the attraction (causing drift current)

[@ShawnDypxz]

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@@keerthanasingaravelan7209 I donate sometimes.

[@rimjhimshukla365]

i have a doubt on the same lines. First of all, i didnt get how they can randomly pop up in the depletion region out of nowhere because there shouldnt be as much thermal agitation in the depletion region as in the other regions. Second, even if they do, there is a 50% probability that they pop up in the p side or in the n side, i,e, there is only a .5 probability of getting swept across the depletion region.