Pn junction Definition and 81 Threads

I need help to understand this solution: Why electric field is zero at x < - b? I think it should be non-zero because the electric field from positive and negative ions don't completely cancel each other. How can you know E rises as x approaches zero?

what is it ? please explaining the physical operation of semiconductor diode (pn junction).

I know this is true under thermal equilibrium, but I am not sure why. Why can't the Fermi level be a function of position relative to the pn-junction? How does that follow from thermodynamics/statistical mechanics?

Hi, I'm stuck with the electrostatics of the PN junction. I just can't see why the electric field has to be negative in the depletion regio. The two equations give positive values for the Electric field in the intervals, so how can it be negative?? In the equation for the n regio, there are...

Homework Statement The drift current in a p-n junction is 20μA . Estimate the number of electrons crossing a cross section per second in the depletion region. Homework Equations Drift current is the current that occurs due to formation of holes and electrons in the depleted region from...

Hi. I am reading about the pn junction, but I have a question. When the junction is formed the holes in the p-type material close to the junction diffuse across due to the concentration gradient. This leaves the acceptor atoms in the p-type material negatively charged. My question is: when...

I am having a hard time to find answers to 2 simple questions regarding semiconductors. Firts, at a PN junction diffusion creates a potential step. Why can this voltage not been measured from the outside. The schoolbook answer is, that there are diffusion potential at the wire connections...

Hello Forum, I am looking at the energy levels between the n and p regions of a diode. The p-side has a conduction band that starts at a higher energy (same for the valence band). The n-side has the valence and condution bands that are at lower energy. The Fermi energy line is the same...

Homework Statement I've been reading and I just want to make sure that this is the correct way which pv cells work, I feel this is not correct. I want to find where I am wrong. Once the p and n doped semiconductors are put together some carriers migrate and combine to form a depletion zone...

Hi, Can someone please tell me if it is true that in heavily doped pn junctions, the electric field that prevents further diffusion of holes and electrons is set up more quickly than in less heavily doped pn junctions? Is this essentially because the holes and electrons recombine more...

Hi friends, here's my question. The two terminals of a PN junction are at different potentials so, if I connect a them with a wire i.e. short them, What would happen? Would the potential difference between the two ends becomes zero or what? As far I'm understanding, there would be a flow of...

Homework Statement A semiconductor p-n junction is fabricated where the doping concentration on the p and n sides of the junction is Na=1E18cm^-3 and Nd=1E16cm^-3 respectively. Given that ni=1.18E10cm^-3, T=300k calculate: a) The majority and minority carrier concentrations in the...

[FONT="Times New Roman"] [SIZE="3"]When a PN juction is in the open circuit condition, my textbooks says the following. "The voltage measured between the terminals is zero. That is the junction Voltage Vo does not appear across between the diode terminals.This is because of the contact...

I'm having trouble fully conceptualizing drift current- what I always hear is that it is caused by minority carriers within one diffusion length of the junction being swept across by the electric field that is generated by the imbalance caused by diffusion of electrons. Here is what I am...

What are e and V in exponent of the equation I = I0(eeV/kT - 1)? is it really one variable "eV", as in electron volts, or is e just 2.718... and V for volts?

hi all i need a book about pn junction diode that starts from 0 and goes to 100. I've been reading solid state electronic devices by Ben G Streetman and elementary solid state physics by M. Ali Omar but these are too confusing and a lot of things are not explained like how some equations are...

the formula for Vn should be V_n=(E_f-E_i)/q field divided by charge in the potential like i was taught in high school but why the write it V_n=(E_f-E_i)/KT k in the boltsman constant t is the temprature there multiplication cannot be the charge ?

Hey, I am working on a report and got stuck at two discussion questions. Help & discussion would be greatly appreciated! 1. What factors determine the turn-on voltage of a pn junction diode? Explain its dependence on the factors you mentioned My guess would be that the light intensity on...

folks, when a pn junction diode is formed, electrons in the n type and holes in the p type diffuse. agreed. then how immobile ions are formed at the vicinity of the junction leading to depletion region? how these immobile ions prevent further diffusion? it is being said electrons and holes...

Homework Statement Determine reverse sat current of diode. To show and explain approach. Given-IV characteristics of diode and tabulated values for forward bias voltage from 0-0.8v and corresponding current values. Homework Equations At which point do I need to consider to find the...

Hi all, I would like to know how pn junction work? thanks DaTario

Say we have a silcon pn junction (diode) - i.e., a block of p-type on left, attached to a block of n-type semiconductor on right: anode ------[ p | n ]------ cathode Because of diffusion we get a barrier potention at the junction, which makes the n-side/cathode 0.7V higher...

internel potentiel of PN junction?? so complicated homojunction PN (not polarized), externel potentiel difference applied = 0 Volt . i should demonstrate the equation: e*Vbi + Eg + ( Ec - Ef ) + ( Ef - Ev) = 0 Given: Vbi= internel potential Eg= energy gap Ef = Fermi...

Any idea where I can fabricate a p-n junction of a custom length? I want it to be of a particular length and size, any company that can do it for me? How costly would it be?

I guess my most general question would be: Given a P/N junction. Let's say two circular discs, one P one N. There obviously exists some Vgap, and applying some voltage across it excites the electrons, then it emits light (very basic LED or something). Now, what if you took a piece of wire...

I have looked all over in many textbooks and I cannot find a decent explanation of this. Most textbooks simply say that it is independent of applied bias because all of the minority carriers generated by thermal energy within a diffusion length of the depletion region will essentially get swept...

Why is it that when no voltage is applied across the pn junction, the fermi energy is the same for both regions?

For a PN junction diode, the total potential across the semiconductor equals the built-in potential minus the applied voltage. Phi = Phi(built-in)-Va(voltage applied) My question is what happens when the Va exceeds the Phi(built-in)? Will the Phi = negative? But how come they always...

During the processing of a PN junction diode when the Ptype material and the Ntype material are joined together. The holes tend to diffuse from the Ptype material to the Ntype material and conversly the electrons from the Ntype material diffuse from the ntype material to the ptype material...

A step pn junction diode is made in silicon with the n side having N'D = 2x10^16 cm^-3 and the p side having a net doping of N'A = 5x10^15 cm^-3. 1). Draw to scale the energy band diagram of the junction at equilibrium. 2). Find the built-in voltage, and compare with the value measured off...

when it comes to pn junction in diode, p and n are doping semiconductors. if P and N semiconductor are contacting each other, some holes in P and some electron in N are combined. that is, they are recombined. this recombination caused the current, very small. I was wondering that...