Talk:Electron hole

message: I must congratulate whoever wrote the chair hopping analogy into this article, it makes it the easiest of all the subatomic particle related articles to understand, despite it's harsh concept! Thanks! --Quadraxis 02:28, 9 November 2005 (UTC)
thread_title: Congrats!

message: I'm looking at the pic of the helium atom, and the caption says that when an electron leaves its shell, then the atom gets a negative charge.  Last time I checked, the opposite is true.  Any comments?
Ghostwo 23:51, 16 October 2007 (UTC)
replies: text: Minimal fix implemented.  Archelon 03:01, 22 October 2007 (UTC)
thread_title:  Negative charge? 

message: For the physicist wannabes among us, could you please add something about how electron holes (or whatever you eventually decide to call them) make LEDs work?  They figure prominently, but at the same time obscurely, in the wiki article I read on LEDs a while ago.  And what would be really, really useful, is to compare with ordinary electric conduction (what I learned many years ago sounds exactly like the empty chair analogy).  — Preceding unsigned comment added by 78.228.108.6 (talk) 08:30, 19 June 2011 (UTC)
thread_title:  E-holes and LEDs 

message: Basically current carried by valence electrons in valence band is said to be the hole current and current carried by free electrons (known as conduction electrons) in conduction band is termed as electron current..  — Preceding unsigned comment added by VIV0411 (talk • contribs) 01:41, 12 August 2011 (UTC)
thread_title:  Note 

message: The article prominently features the analogy where an empty seat in an auditorium moves left as one person after another moves to the right. (I've also seen the same thing with an empty space in an almost-full parking lot.) This is intuitively appealing, and worth discussing, but ultimately misleading. If you take it literally, you get the wrong prediction for the sign of the Hall effect for p-type materials. (Also wrong sign for Seebeck effect, etc.)
The missing ingredient is the curvature of the valence band: Electrons near the top of the valence band behave like they have a negative mass, because the band curves down instead of up. So for example, if an electromagnetic force pushes a valence-band-maximum electron to the right, the electron actually moves left in response. The holes inherit this funny behavior from the electrons.
See my detailed explanation on a different website. I would add something like that here (in addition to the auditorium analogy), but I'd like to find a citation first...anyone seen an explanation along these lines in any textbook? It may be in an obvious place, I haven't really looked. :-) --Steve (talk) 20:32, 20 January 2012 (UTC)
replies: text: Done. Kittel pages 194-196 is the same explanation. :-D (Thanks Nanite for pointing that out.) --Steve (talk) 16:12, 7 June 2013 (UTC)
replies: text: Very Good Example, simply the Best for intuitive understanding, and that it's for Hole in semiconductors (problematic and uncleared thing)!! Nice Work!! --Vanquisher (talk) 18:54, 7 June 2013 (UTC)
thread_title:  Shortcomings of auditorium (or parking lot) analogy 

message: From http://en.wikipedia.org/wiki/Electron_hole
"The concept describes the lack of an electron at a position where one could exist in an atom or atomic lattice. It is different from the positron, which is an actual particle of antimatter, whereas the hole is just a fiction, used for modeling convenience."
From http://en.wikipedia.org/wiki/Dirac_equation#Hole_theory
"In certain applications of condensed matter physics, however, the underlying concepts of "hole theory" are valid. The sea of conduction electrons in an electrical conductor, called a Fermi sea, contains electrons with energies up to the chemical potential of the system. An unfilled state in the Fermi sea behaves like a positively-charged electron, though it is referred to as a "hole" rather than a "positron". The negative charge of the Fermi sea is balanced by the positively-charged ionic lattice of the material."
I am not an expert on the subject but I would like to see this resolved!  — Preceding unsigned comment added by Dudekahedron (talk • contribs) 15:04, 12 August 2012 (UTC)
replies: text: I do not think these paragraphs contradict each other ... if you do think that, could you explain a bit? --Steve (talk) 22:39, 12 August 2012 (UTC)
thread_title:  Discrepancy Betweeen Electron Hole Article and Dirac Equation Article 

message: I found this page looking for an article (or link) on electron-hole pairs. Should there be such a page? Or did I miss it? Gah4 (talk) 17:15, 4 May 2015 (UTC)
replies: text: The link electron-hole pair redirects to the page carrier generation and recombination. If you want to write a better description of electron-hole pairs, I would suggest adding it to that article, rather than creating a new one. Of course if the pair is bound together then that's in the scope of the exciton article... --Steve (talk) 17:50, 5 May 2015 (UTC)
replies: text: Most likely that is just fine. Somehow I found this page instead. Though carrier generation and recombination is written in terms of semiconductor device physics. I was looking for one to link from Photography related to the physics of silver bromide. Light also creates e-h pairs in AgBr, which is the basis for AgBr photography, but isn't exactly the same as in device physics. Gah4 (talk) 18:20, 5 May 2015 (UTC)
thread_title:  Electron-hole pairs 

message: There is a new section on "hole superconductivity" that sounds suspiciously like original research. I didn't yet decide to remove it, but I do wonder. The part about the band structure of superconducting metals should be easy to find a reference for, and that is probably fine. But it looks like it goes farther, including disagreeing with BCS. Gah4 (talk) 05:05, 23 September 2015 (UTC)
replies: text: I just deleted it. Even if the theory is notable and referenced to reliable sources, I think it's undue emphasis. Holes are such a fundamental concept that they play a role in literally every aspect of the electronic behavior of solids. Of course holes are important in superconductors, just as they are important in magnetism, in the quantum hall effect, in the thermoelectric effect, in lasers, in transistors, etc. etc. --Steve (talk) 00:53, 28 October 2015 (UTC)
thread_title:  Hole superconductivity 

message: The [Picture] section states:
 Electrons near the top of the valence band behave as if they have negative mass
However the [Mass] article states:
 For energy eigenstates of the Schrödinger equation, the wavefunction is wavelike wherever the particle's energy is greater than the local potential, and exponential-like (evanescent) wherever it is less. Naively, this would imply kinetic energy is negative in evanescent regions (to cancel the local potential) ... this means that any evanescent portions of the wavefunction would be associated with a local negative mass–energy
And the [Mass] article states:
 One remarkable property is that the effective mass can become negative, when the band curves downwards away from a maximum
Together, this suggests the section should read:
 Electrons near the bottom of the valence band behave as if they have negative mass
— Preceding unsigned comment added by 100.8.0.181 (talk) 20:26, 25 October 2016 (UTC)
replies: text: I believe they are two different effects, though I am not sure I can explain why.  Electrons in a full band aren't effected by an electric field, unless it can supply enough energy to get them out of the band. Electrons at the top of a band have negative effective mass, though at the bottom have to have positive effective mass.  Gah4 (talk) 23:31, 25 October 2016 (UTC)
replies: text: The section you quoted from "Negative mass" is weird and confusing. I think you should ignore it—in fact it probably should be deleted. If an electron wavefunction has an evanescent tail—an extremely common situation—it does not mean that the electron has "local negative mass-energy" in any sense I can understand. I think the author of that section was basically confusing and conflating some largely-unrelated concepts. --Steve (talk) 19:50, 27 October 2016 (UTC)
replies: text: You need the negative (effective) mass to explain the difference between the moving empty seat analogy, and actual holes.  But evanescence is related to negative kinetic energy and tunneling, where the mass is positive.  I suspect that the article could explain the difference between effective mass and real mass better. Gah4 (talk) 20:40, 27 October 2016 (UTC)
thread_title:  Confirm "detailed picture" ? 

message: It would be nice if someone would add a bit of history about who actually introduced the concept of holes into condensed matter and how it is related to the concept of holes introduced by Dirac for elementary particles (Fermions).  — Preceding unsigned comment added by Iskander32 (talk • contribs) 22:46, 12 February 2019 (UTC)
replies: text: Yes, it would be nice to know the story better.  As well as I know it, during WW2, point contact silicon rectifiers were used in radar.  At one point, someone had a silicon rod that was (they didn't have the name yet) p-type on one end, and n-type on the other.  That is, when you made a point contact rectifier, it had one polarity one one end, and the opposite on the other end.  This then led to intentional doping of semiconductors p-type and n-type, and PN junctions.  The transition from point contact transistors to alloy junction transistors, and then better understanding of bipolar transistor theory would have led to the idea of holes. As is usual with inventions, much of the understanding that should have come first, actually came later.  Gah4 (talk) 21:20, 14 February 2019 (UTC)
thread_title:  A bit of history 

message: The number of holes might be small compared to the number of atoms, and still be large. Each band has two states (which may or may not contain electrons) for each atom in the crystal, so about 1023 for a small sample. One ampere is about 1019 electrons (or holes) per second, so we are not talking about a few electrons in most cases. Gah4 (talk) 15:28, 13 March 2019 (UTC)
replies: text: I agree that a reader could potentially be confused when we use "just a few" to describe maybe a quintillion missing electrons per cm³. You're welcome to tweak the wording, e.g. "missing just a few (relative to the total number)" or "missing just a small fraction of its electrons" or whatever. --Steve (talk) 13:42, 15 March 2019 (UTC)
replies: text: I am not so sure what happens when it gets to be much more.  It gets more interesting in metals, where bands are closer to half full. As well as I know it, a group II metal, which has the number of electrons to fill a band, instead has one that is a little less than half, and another a little more than half. Less than half will be an electron band, and more than half a hole band. But even for semiconductors, there can be many holes in an almost full band. Gah4 (talk) 14:10, 15 March 2019 (UTC)
thread_title:  ''missing just a few electrons'' 

message: There seems to be much discussion about hole being, or not being, particles.  In solid-state physics, hole and electrons are both treated as waves, and not particles. The confusing thing, for many of us, is that even though they are waves, they still come in discrete amounts. You can have one or two, but not 1.5 of them.  On the other hand, electrons can travel through vacuum, as in vacuum tubes, while holes can't.  But that doesn't happen in solid-state physics. It doesn't seem to me, though, that the idea of quasiparticle makes this any more obvious to someone who doesn't understand Bloch waves. It also helps to understand Fermi exclusion, which is the thing that allows for holes in the Fermi sea. In any case, I vote for less discussion of quasiparticles. Gah4 (talk) 01:12, 30 June 2021 (UTC)
thread_title:  particles