[11] 반도체 기초_13

Now I am going to talk about the PN diode. Diode means coexisting which is the junction of the P type or N type put together surface by surface. something what is the N type or P type the band structure we can compare what it is here conduction band N type, balance band N type

conduction band for the P type balance band D P type so which is the P doping means this is the middle point. This is FI. But this is getting lower. This is the formula for P type. How about this? This is N type. This is the middle point. Something like FI.

So this is doping and doping. So this is formula moving up. So this is all about the clearly different thing is N type and P type. And this is the work function. E vacuum level until 2d. which is current Fermi level P-type work function is vacuum level to the current Fermi level

which is P-type Fermi level this is n-type Fermi level here this is work function so this work function tells you about the contribution of the carrier where it is, which is the MALL, N-type, located upper level, and P-type is the lower level. So this is the PN diode.

PN diode means something we just put together P-type or N-type, that is the surface junction which is coexisting. Space charge region electric field force acting on the charged carrier. This is Psi. This is Nsi. But this is barrier. Which is what? P-type is this region, the region is something acceptor, which is ionized.

And here is the electron ionized, the space charge region, which is something different, power, that is electric field. Diffusion force on the hole into the destruction Diffusion force in electrical moving to the destruction which is shown here electrical diffusion destruction hole diffusion destruction

So this is the doping profile for ideal uniformly doped to the PN junction case So this is PN junction diode Now I just put together P type and N type device put together. So this is the surface of the contact point.

So this is the Venn diagram for the PN junction. It's P type, the N type. So when you separate the intrinsic formulevel here, and here is a line. But if we put together, once put together, this form it up. This is EFN.

This is the line of the intensity formula. The difference is the bias. The voltage VBI. This is the same thing, conduction band, this much shift, same distance. How about here to do here, the same distance.

This value, this value, this value is the same. So we talk about this one, how much shift, this is the same. So shift up or down is this much difference with the conduction band here and the balance band here based on the intrinsic formula shift up, this much, and this much

This is the band structure for PN junction in equilibrium condition When you align the up P is shift up and is little bit down So that is why lines are perfect. So this is the figure for the PN junction for N side, charge is plus is more.

P side is minus is more. So this is the charge distribution in PN. this is the barrier this side and then this side plus charge minus charge the next is the energy band diagram for the p-n junction okay so this is what i've been talking about the e vacuum level here

here is the old way bottom balance band for electron, balance band for hole, conduction band for electron, conduction band for hole so lined up this is 4 mm for electron here all the way up to here and this is the formular for electron lined up here and this is the intrinsic formular for electron here

and intrinsic formular for electron in here so this is the So in barrier, this is for N type here. So this is the ionized plus and this is the electron. here, ionize the ion, holes in here

here is the electron, this is donor ion, this is the acceptor ion This is band gap for EG electron band gap for hole and something is polarized, something electron or hole, there is electric field plus and minus in here

This is definitely something I've been talking about the bias intrinsic voltage here in previous page So in here is N type silicon and P-side silicon is joined here co-existing This is the ionized, something plus in here plus in here, ionized minus in here minus in here This is the junction with, we call it W

This is much with So another one is the work function, work function is here work function is the whole way formula for electron to the vacuum level and formula for hole for the formula to the vacuum level ok so this is the work function

work function is equal to energy difference between vacuum level and the Fermi level Fermi level means not intrinsic this is something EFN or EFP related to this means here and here, this is the Mock function

so, I want to talk about equilibrium equilibrium is a column flow in homojunction Pn already I talked about what is the band structure, conduction band, balance band formula here which is EFN EFP = here

so this is some barrier, there is something carrier and then they have a behavior or something depends on the polarity the built-in field that transfers the region caused drift current exactly opposite diffusion current resulted from deep carrier concentration along the junction G means R means recombination

so here something electron drift, electron diffuse, other direction hole drift, hole diffusion, other direction current, that's the for drift means here and then drift here, the diffusion in here also electron diffusion current here and then drift current here

so electron is opposite direction to the current but hole is the same direction with the current in the carrier, the electric field in here, the barrier so current generation is this way the electron is this way means the other way the combination reaction is also the current generation can show up here so there is some there is a bit called equilibrium condition

I'm gonna talk about equilibrium so equilibrium means what is the definition something is not active means something steady which means no current. I want to see one by one status.

So in current, there are two definitions which are drift and diffusion. So look it up here. We know what is built-in field epsilon in transition region. In that, electrons are diffusing from D. They have region for high concentration which is N-type. So electrons are energy rich. concentration to D, low concentration which is Psi.

There is diffusion. Here is N or P. Here is electron is rich. High concentration to low concentration which is diffusion. There is also the built-in electric field in a junction. there is electric field, there is produce electron drift. Electric field means something voltage. Voltage means something power energy transfer to electron carrier drift. That which is exactly cancel the diffusion current every car. So drift current

cancel the electron diffusion okay so cancel each other okay so and similarly holes are diffusion from P is rich here to here right but electric field falls back to the tower so electric field P is horizon rich and here is diffusion but drift is push back to the here, which is cancel each other, cancel each other, cancel each other, which is diffusion

for electron is moving diffusion but drift current move back here so hole is moving here by diffusion but back to the drift so which is diffusion and drift cancel each other, which is something is moving and the back to the original point which is none of the work is done so which is no work done means no color which is enough color right sure right so we know what is drift diffusion is cancel each other which is the equivalent

The other concept is generation or recombination which is G and R cancel each other So take a look here, so what it is electron generation and then recombination occur through the device The generation and recombination weight are equal means equilibrium Since there is no fuel in the region, there is no concentration ingredient. So, the generation recombination process is not counted with colors, which is generation recombination, cancel the charge, nothing.

Breed to diffusion, cancel the charge, nothing, which is no concentration. So we knew what it is. So is it current flow? No. By junctioning N or P put together but something is motion but work is done nothing. So which means no current. Just put the device P and put together no current. So equilibrium, so again the generation, the current in the center point N to the peak

which is the electron generated transition region accolades towards the N side producing current from N to the peak Also, hole produces the same generation or accelerated to the peak Okay, which is recombination electron produces a current and opposite direction that I talked to before entering depletion region from the N side recombine whole P side

right the recombination this produce the net column from P to the N so now in conclusion the equilibrium generation recombination rate any position equal So, generation, recombination, current is zero. This is pretty much clear. So now, up to now I just said no current status.

No current means equilibrium. So now I'm going to talk about some actions which is active which is a forward bias the other one is a backward bias which is operating something operating how operating I want to So forward bias, what it is? Something previously equilibrium is no power outside but now I just connect the one side

P type is plus and my negative time P type is negative What is going to be changed? This is the current electric field applied to this direction. This is the electric field generated by ESSA. What it is? Take a look here. PN junction is a fold bias. Bias voltage showing the interaction of electric field by ESSA. Vd, this is Vd, something current went through this direction.

The direction of the electric field zero bias to PN junction, this one. So fold bias, fold bias P type plus N type P minus is reduced barrier okay previously some barrier here right something barrier here to do here but reduced barrier means something which is reduced this much this much so this is this much reduce something built in voltage is by driving voltage here

okay so this side is also reduced by something this much so forward bias means something reduced to better okay so easy to control okay this is it forward bias so more explanation here so which is something join rhythm, something is a which is here is something plus and

this is a P type, this is N type is minus which is a built-in voltage previously this much high but something barrier reduced this much how much? this much something this much reduced This is the operating voltage. This much reduced. Which means it was here but moving up here. It is increasing electron potential energy. Increase means reduced. Here is what? Decrease electron.

This much decreased potential. totally this one this one plus something reduced to value okay so this is equilibrium also but fold bias is reduced to this much same thing so which means even the biased width with something width for equilibrium is this much big but fold bias is reduced this much So, positive or fold bias applied across the junction, which is the transition with both decreasing shown here.

The Psi made electrically more negative, present higher potential energy for electron. The side of energy when the F moved over This is something beside which is more negative which means something down The more negative means something down

which is inside one. Inside is more positive. Here is more positiveLAUGHTER representing lower potential electrons inside moving here is a downward which is a downward. So total barrier is So this is the whole thing about the fold bias Next one is the fold bias which is something minus carrier diffusion current

okay so which is the case recombination current here recombination current here which is something generation or recombination the equilibrium electron concentration here equilibrium hole concentration here which is a hole is more generated more here about here is the excess electrons and more concentration okay so excess electron

and hole is something is it because the tunneling of course constant energy the tunneling may happen so no allowed state something same energy across the gap Electrons cannot turn on from the balanced band P side to the N side Electrons here balance to the P side balance to the P side balance to the P

this is something so electron pn junction regards bias leakage current is small compared to the current for bias okay so on the fold bias the drift current is slightly reduced by something diffusion current okay so this is something something reduced to something performance This is for forward bias. Now I am going to talk about the backward bias.

Backward bias means something P in here is negative. This is opposite from the previous. And type positive. So what is it going to be? So electric fuel in the same direction. So this barrier, this barrier is greater. So backward bias showing some traction of electric fuel. Okay, this one. And then traction of electric fuel zero bias is something this one. Okay, backward bias increases the barrier. So thisLAUGHTER.

the barrier is higher, not smooth, not crunch or something so this is a backward bias so backward bias is something here this equilibrium was here, but this barrier is greater reverse bias. Reverse bias is something greater than previously equivalent. This is decreasing electron potential energy or increasing electron potential energy.

things about the junction of equilibrium bias so bias was here but reverse bias is much larger this is width junction width is larger this is solid line equilibrium bent diagram dashed line is something reverse bias The field increase requires more ionized acceptor donor so that the deposition region gets wider.

Applied negative bias effectively increases potential energy variable both electron and H. So this is the charge result of ionized impurity. Transition of region must be expanded to 1 side. Therefore, the transition region increases like this.

the backward bias which is I want to compare with equilibrium this one and then backward bias equilibrium there is something diffusion current and then drift current is cancelled down which is something this one and then this one is a here is the hole diffusion drift canceled down and generation recombination canceled down

so this is no current but something reverse the case something different okay the charge distribution here something this is drift, this is some diffusion range here so something about this barrier is increased so that's why backward is more here

with reverse bias electron and time material is major carrier to have to diffuse toward P to lower concentration but there is a potential barrier here, potential barrier is very much high the negative amount of electron is enough kinetic energy, which is G/ is very difficult. Get over is very difficult. So it is a thermite energy barrier. Okay so very much difficult. For the rest of the electron,

it travel to the right, the kinetic energy decreases then eventually stops. It is not enough energy to get a barrier. This product is negligible in that current cluster. So, in here, a few conduction band P region. left right here something is a minor carrier diffusion this is a minor only small current

majority is too much barrier so it is not getable which is a leakage current no on purpose so this is no good. so which is from the generation and tunneling current the generation current which is electron balance band being excited to conduction band then sweep to the end reason. why? because too much barrier so then sweep to do

which is the whole produced generation sweeping to do Psi. Why? Because too much big barrier. So recombination is negligible under reversed bias. which is only generation current. The combination is very small, negatively and what is tunneling current? which is some electron balanced electron can tunnel through the forbidden band region

which is something, band structure here. So this is too much barrier here. Not can get over here, not get over here but something is transferred here to here, here to here, which is tunneling car because the electron is a balance band in the P side of tunnel through to the Dixom, conduction band normal and side, it is shifted in left and the other one is carrier multiplication, the electron and hole is called it may happen in depletion region, which is a junction

junction region is produced electron or pair. So only small number of carriers are diffused the other one is something big barrier, drift is very difficult but drift across the junction. to the other side. With increased reverse bias, the value is bigger than reverse currents increase due to the tunneling or carrier multiplication.

With this one, reverse currents are going to be increased. by what? increase increase reverse by more and more something reverse column to increase so now on energy band again for the heat ray junction which I just combined and put together this is something about the P-type which is separately

but once put together, I want to summarize here so this thing is something attached, something potential value something about from here to separate N or P device put together PN junction PN junction to Y. So this is what is the heterogeneous junction

built by electron pn. Once put together, we just fold bias and then backward bias or reverse bias. This barrier is decreased here, which is predicted. Something solid line under reverse bias and the fold bias here is decreased. This is increased. The barrier is bigger. small line. So this is the last line. So something is about the p and i.

For old bias, we know what it is. Positive bias in p side. Backward bias is negative. So p side is something positive bias is something barrier is decreased so current is increased. driving voltage is something positive. one negative is this is reverse. it is a backward. this is reverse is 4. which is very much current increase which is old bias. this is

almost nothing just liquid color which is back old biocene here and then old biocene this portion this is all about the PN diode behavior of the carrier I am just to talk about it Thank you.