@LOLittleHero The electic field produced stops the movement of charge. When you forward bias the junction, this field is overcome and allows the charge to flow again.
@metroidhunter444 5: The hole is just a space for an electron. It just seems or acts as though it has a negative mass and a positive charge.While you could pick up an electron (if you were small enough),u could never pick up a hole.So to answer your question finally, why don't the holes and electrons 'cancel' eachother out? Only electrons are ACTUALLY there.There are not 'hole particles' with which the electron can cancel.It's just the maths which says that a hole can LOOK LIKE an anti electron
@metroidhunter444 4: The mass of this space left by the soldier seems the same as any other soldier and its speed is the same. You could say that the soldiers 'add' mass and the holes 'take' mass. So the hole has 'negative mass'. Anyhoo, going now to the PN junction. As the junction is forward biased, all the electrons are attracted to the positive terminal (leaving holes in their places). It seems as though all of the holes and electrons switched places. However, the hole is not a particle.
@metroidhunter444 3: So say you now look at the valence band, it's partially filled with electrons and space exists where some electrons left to go to the conduction band. Doing the maths (pretty complicated) its found that these holes BEHAVE as though they had negative the mass of the electron and positive the charge on the electron. Imagine an army of soldiers marching and one soldier falling out. The 'hole' left by the soldier seems to march onwards too.
@metroidhunter444 2: The filled band of hightest energy is called the valence band. The lowest unfilled band is called the conduction band. Now some electrons can leak into the conduction band from the valence band (uncertainty principle, extra heat etc. cause this). So as an electron leaves the valence band and enters the conduction band, it leaves a space or a 'hole' in the valence band.So really, you could say that the conduction band is filled with 'holes' and the valence band with electron
@metroidhunter444 1: What is a hole? If you think of the Bohr model of the atom, there are shells in an atom which can be unfilled, partially filled or filled with electrons. If partially filled, you can think of a shell or orbit as having 'holes' in it. Extending that analogy to metals. The electrons in metals form bands (similar to the orbits in an atom). These bands are kinda like groupings of the atomic orbits. So groupings of energy levels exist.
@MultiSuperdarren Part 1 Ok there are a few answers to that question. The simplest is to draw to small vertical lines on a page, with a horizontal line going left and right away from them (your drawing would then resemble a capacitor). Label one vertical line P and the other one N. Now if you forward bias the junction (putting a + voltage on the P type and a - voltage on the N type) your holes will be repelled by the positive voltage, your electrons will be repelled by the negative voltage.
@MultiSuperdarren Part 2 However they the repelled electrons and holes will be pushed closer to the physical pn junction (where the two materials touch), shortening the depletion region. If you can understand that, they you can accept that by reversing the voltage, the holes are attracted (away from the junction) and the electrons are attracted (away from the junction). Thus the depletion region grows in size. Hope that helps
@youspinmerightrounds so lets say the depletion region grows when it is reversed biased, wouldn't the electrons from the cathode of the battery flow towards the P, and the electrons from N flow towards the anode? There should be a flow of current right?
@MultiSuperdarren Nope, when reverse baised, there is actually no circuit. When forward baised, since the depletion region reduces, eventually there is conduction across it. Thus if your diode is connected via wires to a voltage source, then you have a complete circuit. Current flows from the voltage source through the diode, back to the source. When reverse biased, the depletion region is too large for conduction. So a complete circuit does not exist and no current flows.
Thank you so much. But I think in reverse bias, the diode still conducts, but in a very small amount compared with the forward bias. By the way, I am also stuck by the PN junction under bias. We all know that in forward bias, the diffusion is the major mechanism, but how does the excess carrier forms? I have read quite a lot of lectures and books and cannot find a satisfactory explanation...
great video, really helpful. Just one thing, when you dope a substance to create a P-type semiconductor you add elements from group 3 and when you create an N-type you add group 5 elements - i think you got them mixed up.
Thank you :)
desjoh1 1 week ago
the voltage required to shrink the depletion region is called?????????please tell me....
ZOOM4461 2 weeks ago
Great explanation, simple and logical.
NagaJolokiafied 1 month ago
great video!! thanks for it!!
santipagola1993 2 months ago
Clear, straight forward, great! Thanks for creating this! :)
mohawkalex 2 months ago
in your notes, your electric field is going from p side to n side... but shouldn't the electric field go from n side to p side???
carab118 2 months ago
@carab118 yip you're right never changed that, should though thanks!!
youspinmerightrounds 2 months ago
Good work! No fancy Computers or slides used to explain things vividly!
TBishesh123 2 months ago
why does it conduct when the depletion region is reduced?
thanks for the vid
LOLittleHero 2 months ago
@LOLittleHero The electic field produced stops the movement of charge. When you forward bias the junction, this field is overcome and allows the charge to flow again.
youspinmerightrounds 2 months ago
@metroidhunter444 5: The hole is just a space for an electron. It just seems or acts as though it has a negative mass and a positive charge.While you could pick up an electron (if you were small enough),u could never pick up a hole.So to answer your question finally, why don't the holes and electrons 'cancel' eachother out? Only electrons are ACTUALLY there.There are not 'hole particles' with which the electron can cancel.It's just the maths which says that a hole can LOOK LIKE an anti electron
youspinmerightrounds 3 months ago
@metroidhunter444 4: The mass of this space left by the soldier seems the same as any other soldier and its speed is the same. You could say that the soldiers 'add' mass and the holes 'take' mass. So the hole has 'negative mass'. Anyhoo, going now to the PN junction. As the junction is forward biased, all the electrons are attracted to the positive terminal (leaving holes in their places). It seems as though all of the holes and electrons switched places. However, the hole is not a particle.
youspinmerightrounds 3 months ago
@metroidhunter444 3: So say you now look at the valence band, it's partially filled with electrons and space exists where some electrons left to go to the conduction band. Doing the maths (pretty complicated) its found that these holes BEHAVE as though they had negative the mass of the electron and positive the charge on the electron. Imagine an army of soldiers marching and one soldier falling out. The 'hole' left by the soldier seems to march onwards too.
youspinmerightrounds 3 months ago
@metroidhunter444 2: The filled band of hightest energy is called the valence band. The lowest unfilled band is called the conduction band. Now some electrons can leak into the conduction band from the valence band (uncertainty principle, extra heat etc. cause this). So as an electron leaves the valence band and enters the conduction band, it leaves a space or a 'hole' in the valence band.So really, you could say that the conduction band is filled with 'holes' and the valence band with electron
youspinmerightrounds 3 months ago
@metroidhunter444 1: What is a hole? If you think of the Bohr model of the atom, there are shells in an atom which can be unfilled, partially filled or filled with electrons. If partially filled, you can think of a shell or orbit as having 'holes' in it. Extending that analogy to metals. The electrons in metals form bands (similar to the orbits in an atom). These bands are kinda like groupings of the atomic orbits. So groupings of energy levels exist.
youspinmerightrounds 3 months ago
how does the depletion layer grow in size when it is reversed biased?
MultiSuperdarren 4 months ago
@MultiSuperdarren Part 1 Ok there are a few answers to that question. The simplest is to draw to small vertical lines on a page, with a horizontal line going left and right away from them (your drawing would then resemble a capacitor). Label one vertical line P and the other one N. Now if you forward bias the junction (putting a + voltage on the P type and a - voltage on the N type) your holes will be repelled by the positive voltage, your electrons will be repelled by the negative voltage.
youspinmerightrounds 4 months ago
@MultiSuperdarren Part 2 However they the repelled electrons and holes will be pushed closer to the physical pn junction (where the two materials touch), shortening the depletion region. If you can understand that, they you can accept that by reversing the voltage, the holes are attracted (away from the junction) and the electrons are attracted (away from the junction). Thus the depletion region grows in size. Hope that helps
youspinmerightrounds 4 months ago
@youspinmerightrounds so lets say the depletion region grows when it is reversed biased, wouldn't the electrons from the cathode of the battery flow towards the P, and the electrons from N flow towards the anode? There should be a flow of current right?
MultiSuperdarren 4 months ago
@MultiSuperdarren Nope, when reverse baised, there is actually no circuit. When forward baised, since the depletion region reduces, eventually there is conduction across it. Thus if your diode is connected via wires to a voltage source, then you have a complete circuit. Current flows from the voltage source through the diode, back to the source. When reverse biased, the depletion region is too large for conduction. So a complete circuit does not exist and no current flows.
youspinmerightrounds 4 months ago
@youspinmerightrounds Oh I see! Thanks! God bless!
MultiSuperdarren 4 months ago
Thanks man! I can't even understand my prof. He no speak the English! But you do!!!!
SDTricker 4 months ago
@SDTricker Great! Always glad I can help!
youspinmerightrounds 4 months ago
THANK YOU SO DAMN MUCH!! Fucking teacher I have doesn't know how to teach.
noelito01 4 months ago
@noelito01 Thanks for the positive feedback! Glad it helped!
youspinmerightrounds 4 months ago
I love u
Saifismcgill 4 months ago
@209hii Actually, this lesson is taught at schools at the age of 16. So you are still normal.
Yamboist 5 months ago
@209hii it sure is! This stuff is pretty basic but it's this sort of things which gave us computers, radios etc! glad you liked it!
youspinmerightrounds 6 months ago
im 16 years old and im watching this, and i get it, and im into this at the same time. is that normal?
209hii 6 months ago
Thank you so much. But I think in reverse bias, the diode still conducts, but in a very small amount compared with the forward bias. By the way, I am also stuck by the PN junction under bias. We all know that in forward bias, the diffusion is the major mechanism, but how does the excess carrier forms? I have read quite a lot of lectures and books and cannot find a satisfactory explanation...
fastjacksonmin 8 months ago
Everything explain shortly and I really like it.Just one mistake :the direction of electric field vector is from + to -
rolastan 8 months ago
great video, really helpful. Just one thing, when you dope a substance to create a P-type semiconductor you add elements from group 3 and when you create an N-type you add group 5 elements - i think you got them mixed up.
paddyxg2 8 months ago 7
@paddyxg2 you're dead right! i suppose i should be more accurate with my descriptions! cheers, i'll put an note on the video soon. adam
youspinmerightrounds 8 months ago
cheers mate !!
jwaint06 9 months ago
Very helpful insight, good work
marccram 9 months ago
Very nicely put. You filled in the holes for my first lab report.
mattandkacie 1 year ago