PN Junction Diode (Forward-Bias Condition)
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- เผยแพร่เมื่อ 22 มี.ค. 2016
- Analog Electronics: PN Junction Diode (Forward-Bias Condition)
Topics Covered:
1. PN junction diode in forward bias condition.
2. Effect of forward bias potential on depletion layer.
3. Effect of forward bias potential on barrier potential.
4. Effect of forward bias potential on reverse saturation current.
5. Diode current.
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Well explained! Thanks so much .I was really having a hard time to understand my lecture notes. I like the way you are slowly explaining and breaking down the steps.
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Excellent explanation. Thank you
very clearly explained! Thanks a lot
when external vtg = barrier potential at that particular temp, is it true that the depletion region is ideally of 0 thickness?
Thanks for your valuable videos 🙏
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Can you please tell us, what reverse saturation current is?
Here the diffusion current due to the majority charge carriers flows under the effect of the external bias. Can it thus be called the drift current (as per the meaning of drift current)?
sir can u plz explain y the direction of diffusion current is from p side to n side nly. n thanks for the videos
thank you sir.i will learn lot from ur lectures..i have some doughts plz clarify them
sir,was the diode current in forword bias is due minority carriers also???
plz explain the concentration of minority carriers on either side(p and n) when the pn-juncion is forward biased??
Sir the diffusion current that you talked about, does it exist after the applied potential becomes larger than the barrier potential or does it exist if it is smaller??
Sir, in the video (at 5:17) you said that Is (drift current-due to minority charge carriers) remains constant, but it is the amount of minority charge carriers that depend on temperature and not the current as after applying the positive bias even though the charge carriers(minority) remains same(as temp is constant) but the current will be decreased since the minority charge carriers will have to surpass the external electric field to generate the electric current... Isn't it ??
thank you for the videos and all your hard work. really appreciate it. is there any playlist for these videos on semiconductor topic?
thank you :)
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Really good! Thanks!
why reverse saturation current has opposite direction though external potential applied and it affected barrier potential effectively?
Why does no current flows through a diode in Reverse bias mode?
Tq sir,i am greatly beholden to you, i have learned a lot
nobody explained in detailed like u Sir,tq very much
is these videos also for competetive or only for board point of view?
very very thanku ....bhai....ur vedios are awesome....
best explanations!!
Sir u said when forward bias potential applied free electron and holes recombine with opposite ions to reduce the depletion region..can free carriers recombine with immobile charge carriers ?
Yes
I think this is wrong in this video. The bonds need to break before that, don't they?
The voltage we apply will allow this to happen
Exactly that's why my teacher don't accept the the word 'recombine'. I need a better explanation.
@@jan861Please explain. I need this answer.
I have a doubt...when I applied FB,u said the holes from P side will combine with the negative ion in the depletion layer...but to do this the hole is releasing it's negative ions...then the width of depletion layer should be same as before...right?(Although I know I'm wrong,I just don't know what am I missing.)
...when that combination (holes from P side + immobile ions -ve in the depletion region = recombined ions) happens, recombined ions now belong to the P side. Now the depletion region has lost some - ve ions (now called recombined ions). Losing -ve ions = losing some place in the depletion region. That lose results in lose in the width. So it is, decrease in the width of depletion region.
And depletion region /layer's can't be same.
(Hope I'm not wrong...!!)
Hi Sir some question, Wd will increase or decrease when Na or Nd higher? Thanks
If new Vb = Vb - Vd, then if Vd is > 0.7 will the new Vb < 0?
How is that possible?
Is revers saturation and drift current is same?
Thank you so much for the videos. They are really very clear to understand. can you please explain why the diffusion current flows from P side to N side.
i guess it is because we take that current flows from positive to negative
its bcz n side has more electrons and p side has holes so electrons from n side moves towards p side to fill the hole and electron flow starts from n to p and we know electric field is always opposite to the electron flow so current will flow from p to n .
Sir,
I have a doubt, shouldn't the formula for barrier potential should be written in reverse order as the applied potential is of higher magnitude?
please reply me.I think there is mistake in p type ,there is showing electron and n type there is showing holes.
Sir u said minority charge carriers depends on temperature does not depends on external field but in reverse voltage increases why the diode going to breakdown
Thanks a lot☺
Sir, i have this doubt that whether reverse saturation current and drift current are both same thing?
Suppose to be so
yep
Lakhan Rarth tq for this
due to the recombination taking place at the junction atoms becomes ions at the junction and hence potential develops across the junction .above process will continue till equilibrium potential ( where the drift current or saturation current will be equal to diffusion current ) develops across the junction and further recombination stops .hope it helps
No they r not the same thing
Sir why only saturation current from n n to p side
Sir, I understood it very well. One question is that why are there +ve and -ve ions on both sides in the no-biased condition?
They are trivalent and pentavalent impurities added
what are these immobile ions ?
for what purpose we use reverse bias....????
Is 'reverse saturation current' is another name for 'drift current'?
What is the difference between the reverse saturation current and the drift current in a p-n junction? Are they same?
How drift current exits if there is no barrier voltage
As barrier potential decreases (when Vd is applied) and eventually becomes equal to or greater than zero..wont the holes on the p side recombine with electrons with holes?
No because potential difference will prevent it.
how the recombination takes place .........?
can any one plzn tell me
why are we considering reverse saturation current in forward bias condition?
It's a very small opposing current. The minority carriers(electrons) in the p side will move away from the junction....as opposed to the majority current. Same is the case with holes on n side.
But from where these recombining electrons and holes come from ?? If the they come from behind the depletion region then the atoms from which they come will become ions which you haven't mentioned here!?
Please answer me
but where is the current of the battery?
Isn't there should be a resulted forward current? Where is the details. Cause that's the point of a junction in forward, not only to decrease the depletion layer right?
Thank you sir 🙏
How can mobile charges make recombination with immobile ions? As far as electron, as majority charge carrier is concern, it is a free electron i.e which has left its valence orbit and left a positive ion behind, then how it can recombine with the same ion, even when a voltage is applied? Pls clear.
My qstn also
sir as u said in a previous lecture dat diffusion current will be from right to left but in this video u r saying dat it is from left to right. Please clear this ambiguity.
Is reverse satuarton current is equal to drift current
What will happen if Vd is greater than Vb ?
Can someone explain why is the drift current not changing when we apply a voltage? I am thinking it's supposed to be decreasing since the depletion layer is smaller
There is some simplification involved, where the smaller drift current is being ignored.
I thought diffusion current is due to the concentration difference of electrons between n and p. Since n has more higher concentrations of electrons, they will go to lower concentration which is the p. This movement of electrons is the Diffusion Current and causes potential barrier. While Drift Current is the movement of electrons when there is an external electric field (in the case of pn diode, the potential barrier is where the Electric field resides). And it opposses the direction Diffusion current. So when the concentration of electrons and applied electric field in potential barrier balances the current, net current will be zero hence no current flow.
Is Cut-in/Threshold voltage same as Knee Voltage.?
Simra Abbas yes
thank you so much
Thank you very much sir🥳🥳🥳🥳
Thank you Sir
Sir, which book you follow?? Please provide the name.
Thank you
Thanks sir
under no bias condition how far depletion layer can go?
Until the equilibrium is reached,i.e.,Idiff=Idrift.
Depends on P and N concentrations and semiconductor permittivity
Meghjit Mazumder about 0.5 ampere
Thanks
The direction of diffusion current you say it is left to right. Is it so? Or is it right to left?
Muskan Sharma it will from p to n
Imran Ali thanks
Muskan Sharma pleasure
what is minority carrier injection
Thanku dear
Explain mechanisms of forward baised in pn junctions cha ans ky ahe
You told that if the width of depletion region decreases than barrier potential also decreases but according to the formula of barrier potential, it does not depend on width of depletion layer
Maybe use Gauss's Law for electrostatic:
Del dot E = rho/epsilon
Del dot (-grad V) = rho/epsilon
Nice video
How the direction of diffusion current is left to right...bcz the electric field due to the majority charge carriers is right to left..it should be in same as of electric field....????????
ASUTOSH BEHERA drift current has the same direction as electric field.. not diffusion current.. diffusion current has direction of diffusion of holes ( conventional current)
Sir very very much thanku
good video
I like it
🔥🔥🔥
This is a good one.👍
All the video for gate
Yes or No sir
Just please explain why the direction of i majority from left to right????
Because current by convention in defined for the movement of holes. Remember : Current is not the actual movement of electrons.
because when we connect the voltage the negitive side of the battery push all the electons in (n-region) toward (p-region) of diode thats why its start motion from left to right
Thik h
if depletion layer would decrease so net barrier potential would also decrease and these saturation current are moving due to barrier potential. so if barrier potential is decreasing then saturation current should also decrease???????
Our teacher don't accept the word 'Recombine '
Then what does he accept
Don't you think so that p type contains holes and n type contains electron as given in hcv
but your diagram is opposite...
attracted to the opposite.no,repelled same
Kis kis ko yaha se padh rahe hai kyuki college me thik se samjh nahi atta hai
😪😪😪😪
Difference between Drift currentand Reverse Saturation current in Diode:
The total current in a p-n diode contains both drift and diffusion components of the current. The drift current component is controlled by the electric field, whereas the diffusion current component depends on the concentration gradients present. At different points in the diode the carrier contribution changes from drift component to diffusion component and vice versa. In simple words
Both majority and minority carriers contribute for drift component of the current. The minority drift current component occurs at the p-n junction (transition region), while the majority drift component current dominates at away from the transition region towards the metal contacts deposited on p-n semiconductor
The diffusion component contains only majority carriers. This component usually dominates at the transition region
Therefore, at the junction always two components of current will be present. One is due to minority drift, the other is due to majority diffusion. However, at equilibrium both components of the current gets cancelled with each other, resulting in zero current at the junction.
The reverse saturation current comes entirely from the minority carriers in the p-n junction diode. It is purely drift component of current near the junction, because the minority carriers usually swept by the electric field present at the transition region. The carrier swept happens only if the minority carriers are generated with in the diffusion length of transition region. The minority carrier contribution depends on how often the carriers are swept by the field present at the transition region.
The majority carrier drift current component generally dominates under biasing conditions (say forward bias). The majority carrier contribution changes from diffusion to drift as we traverse away from the junction towards the contacts. Because the applied fields present at the contacts accelerate the majority carriers which are present near the contact regions.
Thus, the drift component current contains both majority and minority carrier contribution. The drift current which comes from the minority carriers is called reverse saturation current and it generally dominates the junction.
mat padh bhai shreyaans
voice is too much low.... disgusting
Santosh Verma increse the Volume button.
bevakoof
Is Cut-in/Threshold voltage same as Knee Voltage.?
Simra Abbas nope