Talk:P–n junction

message: Schottky diodes do not have P-N junctions.  They have metal-semiconductor junctions (See Schottky_barrier) Tonsofpcs 18:52, 13 May 2005 (UTC)
replies: text: Corrected. - mako 18:56, 13 May 2005 (UTC)
thread_title:  Non-rectifying Junctions 

message: The proposed merger of Reverse-biased into p-n junction#Reverse-bias sounds like a good idea. It really is a feature/effect of the junction, not much to say on its own, and need to discuss the junction to understand it anyway. DMacks 21:51, 18 September 2007 (UTC)
thread_title:  Merger proposal 

message: Figure B is mislabeled. Should be "charge density", \rho, instead of "charge", Q. Greengadgetz (talk) 15:38, 13 March 2008 (UTC)
thread_title: Error and question

message: Is there a reason that no mathematical analysis of the operation of a PN junction has been included in this article? 69.134.60.173 (talk) 03:41, 17 March 2008 (UTC)
thread_title:  Mathematical Analysis 

message: I suggest add information about heterojunctions and multijunctions.--Mac (talk) 11:57, 15 September 2008 (UTC)
thread_title:  Information 

message: I think formatting the "See also" section, as edited by 69.225.251.134, looks bad. Since 69.225.251.134 has been making the same change all over the place, I will be opening a discussion on this at Wikipedia talk:Manual of Style. --Jc3s5h (talk) 15:08, 18 July 2009 (UTC)
replies: text: It's certainly bad, and the user has also been making other dubious changes (mostly by subtly changing words, usually with IMHO a detrimental effect), so I have warned them about it. I have to say that, regrettably, virtual every article they edited, as seen on their list of contributions, looks to have been edited dubiously (I think I have fixed most, but I would be grateful if others had a look). --LjL (talk) 16:30, 18 July 2009 (UTC)
thread_title: Format of "See also" section

message: I think diagrams illustrating the effect of turning on forward and reversed bias would be helpful in understanding the physics; especially helpful would be electron/hole energy vs. position diagrams. Zylorian (talk) 01:45, 4 January 2010 (UTC)
thread_title:  Forward and Reverse Bias illustrations 

message: The potential barrier of a pn junction can never be brought down to zero ….nor ever “reversed”, 
however strong the forward biasing voltage. The question then arises: where does the applied voltage drop ? Will it be possible to include the following numerical to illustrate the point ? 
Consider a silicon p-n junction with doping concentrations NA = 2.5 x 1015 cm-3 and ND = 5 x 1016cm-3 at 300°K with the intrinsic concentration ni = 1.5 x 1010.(Problem in Electronic Devices and Circuits by Milman and Halkias). Using expression Vo=VTlnND NA/ni2,with VT=0.026V at 27ºC, we obtain Vo = 0.703 Volts at 300°K and Io = 9.17 x 10-15 Amps and using the formula for current I = Io(eV/VT -1), we obtain for a forward bias V of 0.6V, VT = 0.026 V at 300ºK or 27ºC, current I = 0.1045 mAmps. What we observe here is that a forward bias voltage of 0.6 V which is less than Vo = 0.703 V has caused a current of 0.1mA in the diode. For a forward bias voltage 0.69V < Vo = 0.703V, we obtain I = 3.4 mAmps ! 
An increase in forward bias voltage of 0.09V has caused the forward current to increase by nearly 33 times to 3.3mAmps and the bias voltage is yet less than the barrier potential. With V = 0.7029V < 0.703V (Vo), I = 5.41 mAmps (54 times the value when V was 0.6V)! If a small diode, it will surely burn out with this current !
We assumed that the applied voltage appears across the junction entirely ignoring the voltage drops across the bulk of the p and n regions. It is reasonable to assume that, yet, as the applied voltage approaches Vo = 0.703V, and the current increases, some voltage will begin to drop across the bulk p and n regions (the electric field in these regions increases) and across the resistance of the ohmic contacts to uphold the current conservation law while, the part of the applied voltage that lowers the barrier potential Vo, makes the voltage across the junction close to zero but, not equal to zero and a vanishingly thin depletion region remains that demarcates the p and the n regions with holes (from the p-side) and electrons (from the n-side) recombining all around. Only a small part of the applied voltage lowers the barrier potential Vo. And, after the current reaches 5.41 milliamps or so, the I-V relation will be I = Io(e(V-Rs)/VT -1)where RS is the total bulk resistance of the neutral region. Therefore, up to a certain current level of the diode, the ideal exponential diode characteristics are applicable after which the characteristic becomes nearly linear mainly dominated by the bulk region.
Sridhar Chitta Sridhar10chitta (talk) 00:46, 8 March 2010 (UTC)
thread_title:  The potential barrier cannot be made zero and currents for various forward bias voltages 

message: Not being an expert in semiconductor physics, I'm not sure, but I strongly suspect the figure A.A might not be accurate. Because electrons can recombine with holes, right? Therefore I'd expect that when you enter the charged region near the junction coming from the P side, hole density would start to decrease before electron density increases, or at least, hole density would decrease faster than electron density increases. In fact I suspect that most electrons coming to the P side from the N sides would recombine with one of the holes they find on their way. Same goes for holes crossing the junctions from the P side to the N side, I'd expect most of them to recombine with an electron from the N side. Thus, the first thing you'd see when you get closer to the junction from either side is a decrease of the majority carrier, not an increase of the minority carrier.ThorinMuglindir (talk) 20:39, 7 July 2012 (UTC)
replies: text: Maybe a little, but recombination is actually a relatively rare (low-probability) process; carriers can have relatively long lifetimes and long paths before recombining.  Dicklyon (talk) 06:11, 8 July 2012 (UTC)
thread_title:  electron and holes density in the charged regions around the junctions 

message: What does it do?
You are not telling what is happening at the junction.
Are the electrons having a party there?  — Preceding unsigned comment added by Jangirke (talk • contribs) 04:40, 7 February 2014 (UTC)
replies: text: I agree. I have improved the lead to at least link to depletion region, which is what happens at the junction and what causes the "diode" behaviour. Plus removed some fluff and tried to rewrite the "relationship" between the p-n junction and other devices in a less misleading way. Euan Richard (talk) 01:24, 5 May 2024 (UTC)
thread_title:  confusing 

message: In order to have a precise analysis of p-n junction, it's better to mention the "Donor levels" and "Acceptor levels" which appear in the Band diagram after doping.
http://www.doitpoms.ac.uk/tlplib/semiconductors/intrinsic.php
http://www.physics.udel.edu/~watson/scen103/99s/clas0426.html
http://people.bu.edu/cwinrich/donor.htm
http://people.bu.edu/cwinrich/acceptor.htm
http://www.staff.ncl.ac.uk/j.p.goss/Research/Electrical_levels
Homayoun mh (talk) 17:43, 19 May 2014 (UTC)
thread_title:  Donor/acceptor Levels 

message: Hello fellow Wikipedians,
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thread_title:  External links modified 

message: Hi. I noticed that there is some incorrect information under the "Reverse bias" section. In this section it is stated:
"Because the p-type material is now connected to the negative terminal of the power supply, the 'holes' in the p-type material are pulled away from the junction, leaving behind charged ions and causing the width of the depletion region to increase. Likewise, because the n-type region is connected to the positive terminal, the electrons will also be pulled away from the junction, with similar effect. This increases the voltage barrier causing a high resistance to the flow of charge carriers, thus allowing minimal electric current to cross the p–n junction. The increase in resistance of the p–n junction results in the junction behaving as an insulator."
This information is incorrect because the 'holes' do not actually move; they are positive ions themselves, and therefore will not move through the wire away from the semiconductor, as only electrons flow through conductors (the wire in this case). I am posting this on the talk page to see if any of the long time editors have any ideas or preferences for how we should reword or change this before I go ahead and edit it myself. VirtualLibri (talk) 19:05, 10 June 2018 (UTC)
replies: text: Holes move; they are one of the two mobile charge carriers in semiconductors.  See Electron hole article. --ChetvornoTALK 08:33, 12 June 2018 (UTC)
replies: text: Yes, holes move, in the same way that bubbles in a liquid move. You could protest "but bubbles in water don't actually rise, what really happens is that the water moves downward", but in effect they do move. Geoffrey.landis (talk) 16:22, 23 April 2021 (UTC)

text: They only "move" because of electrons. Protons remain static. I think we have to clarify that when we have an appropriate source. AXONOV (talk) ⚑ 22:36, 5 May 2022 (UTC)
replies: text: This is clarified in the electron hole article which is linked --ChetvornoTALK 06:24, 6 May 2022 (UTC)
thread_title:  Incorrect Information 

message: The section "Size of depletion region" is nearly incomprehensible because the variables are poorly defined.  C_A and C_D seem to be defined both as functions of x, and also as constants.  I will presume that when they are constant, the implication is "concentration of acceptors on the p side of the junction" (and likewise donors), but the equations do not make it clear when the values are constant, and when they are variable.
The final equation
\Delta {{V}_{0}}=\frac{kT}{q}\ln \left( \frac{{{C}_{A}}{{C}_{D}}}{{{P}_{0}}{{N}_{0}}} \right)
makes no sense, because the article already stated a paragraph earlier "where P_0=N_0=0".
Geoffrey.landis (talk) 15:56, 22 April 2021 (UTC)
replies: text: OK, I did a rewrite to try to make the variables clear, and added "in the depletion region" to the specification P_0=N_0=0. (I also moved this up, since it seems to be an assumption used in the charge neutrality equation.)  I also note that the derivation had assumed that the reader knows that donor and acceptor ions are positively and negatively charged respectively, so I made that explicit as well. Geoffrey.landis (talk) 16:19, 23 April 2021 (UTC)

text: I don't really think that this part has any value for outsiders. It's quite technical for ordinary people to understand. Additionaly I would like to see a geomtric explanation rather than a mathematical one. Any chance we can have more sources? That section contain almost no citations. AXONOV (talk) ⚑ 17:02, 16 June 2022 (UTC)
thread_title:  Need to define variables better