Talk:Semiconductor/Archives/2012

Unclassified
"What makes semiconductors useful for electronic purposes is that they have the property of being able to carry an electric current by electron propagation or "hole" propagation". Can't be said with fewer words:

"Semiconductors are useful for electronic purposes because they can carry an electric current by electron propagation or "hole" propagation".

this question about Valence band versus conduction band, and which one is highest or lowest energy? if you add energy, doesn't this excite electrons in the valence band moving them into the conduction band? wouldn't this imply that the conduction band is higher energy? Waveguy

I'm sorry I didn't make this very clear. If you look at the diagram:



The conduction band has a higher energy than the valence band. But the valence band is the highest of the filled bands, and the conduction band is the lowest of the unfilled bands. -- Tim Starling 04:35, Jul 16, 2004 (UTC)

This isn't especially relevant, but in the first paragraph, all the examples of devices with solid-state electronics are (at least from what I know) technically computers. Let's use CD players as an example. It's true that you can't play video games on a Discmantm, I think, but they do use ICs and read digital optical discs. Even the cheapest ones have at least enough RAM for 45 seconds of buffered sound, an 80-track playlist, whether or not the gadget is in "hold" mode or if it has bass boost turned on, what the current volume, level of battery charge, radio station (if applicable,) and audo format is, what position the laser should be at (at level of precision on the order of more than 4.5 million possible positions per inch,) and how fast the disk should rotate (a range of 200 to 500 RPM, down to who knows how many decimal places,) plus whatever other data is required by internal processes. In addition, there must be enough processor power to control all of these processes, decode MP3 files, display stuff on the LCD, and randomly shuffle between tracks, to name a just a few required functions. Then there should be enough internal static ROM to store instructions, what letters to display where on the LCD, etc. While it's true that this is all firmware, it still computes things which is the definition of a computer.

Thus, "Examples range from computers to cellular phones to digital audio players," should read "Examples include nearly all computers, from PCs to cellular phones to digital audio players." —Preceding unsigned comment added by 67.180.200.204 (talk) 00:37, 2 October 2007 (UTC)

Not all semiconductors are inorganic
Defining metals and semiconductors by the temperature dependance of their resistances is a gross oversimplification. The reason semiconductors' conductivity increases with temperature is because thermal energy can promote electroncs across the gap, generating the charge carriers that are actually responsible for eletrical conductivity. It is also true that if you shine light on a semiconductor its conductivity will increase because UV/visible light can also promote electrons (especially in organic semiconductors which tend to absorp in the visible region), but you wouldn't define a semiconductor that way. Anyway, the dependance of conductivity on temperature is a function of doping. Overdoping will decrease the conductivity of a semiconductor, for example the conductivity of poly(thiophene) goes through a maximum as a function of dopant right around 1:2 dopant:thiophene unit. Therefore, fully doped poly(thiophene) will become less conductive when heated because the added charge carriers will cause overdoping. It is also worth mentioning that other non-semiconducting systems can show an increase in conductivity as a function of increasing temperature due to ionic conductivity which often becomes accessible to highly charged, non-conjugated (i.e. lacking a band structure) polymers at elevated tempertaures. It is far more accurate to define semiconductors by their band structure because this is in fact the scientific definition of a semiconductor, while the thermal definition is something that physicists often incorrectly mistake for the definition.Fearofcarpet 21:54, 17 Mar 2005 (UTC) hi

Semiconductor not defined only by energy bands
I added a few words to the definition. (Are those sentences getting too long?) If we place an electron deep within certain insulators (such as a hunk of resin,) the electron will become trapped in place and will not move significantly when an electric field is applied. On the other hand, if we place the same electron inside a semiconductor, the electron will be freely mobile and will easily flow during an electric field. As insulators, semiconductors behave like vacuums do: they lack trapping centers, and the charges injected by doping, etc., are free to move around. I'm not certain, but I think the definition of "semiconductor" leans more heavily on "lack of trapping centers" than it does on "small band gap." For example, doesn't diamond behave as a very good insulator? Yet diamond also lacks trapping centers, and a diamond-based transistor isn't impossible: see diamond-based semiconductors --Wjbeaty 04:42, Apr 13, 2005 (UTC)


 * A diamond is simply a "wide bandgap semiconductor". As such it is less conductive than silcion, but still more conductive than an insulator. Its all arbitrary anyway. I believe a semiconductor is rather loosely "defined" as being somewhere between a "conductor" and an "insulator"


 * By the way, can we have the band diagram on the article page? I shouldn't have to come to the discussion page to find it ;-)


 * Also, I am thinking of creating a page that deals specifically with the band structure of a semiconductor. What do you all think?--darkside2010 17:46, 15 Apr 2005 (UTC)


 * "Its all arbitrary anyway."  Not at all.   While the division between conductor and insulator is certainly arbitrary, "semiconductor" is only arbitrary if we screw up the definition of that word!  Is copper a semiconductor?  How about polyethelene?  If we refuse to draw a line in the sand, then everything is a semiconductor, or nothing is.


 * Here's another possibility: "a semiconductor is a conductive material whose low electrical resistance is caused by mobile charge carriers contributed by very small amounts of impurities."  In other words, if the conductivity is caused by doping, then it's a semiconductor regardless of its band gap width.  And notice that this wording excludes materials which are full of trapping centers (if the material is insulating yet is full of *immobile* charge carriers, then it's not a semiconductor.) --Wjbeaty 22:12, Apr 17, 2005 (UTC)


 * Fair point. An encyclopedia should, after all, define things, and do it well. After reading the opening paragraph of semiconductor again, I think that we could come up with a better definition. So what is it that makes a semiconductor a semiconductor? It has a band gap, sure, but so do all solids - it comes from the quantisation of allowable electron energies around the nucleus. The thing that's different about a semiconductor is that the Fermi level lies somewhere in the bandgap, rather than in an allowable band as it does for a conductor. But then, an insulator also has a mid bandgap Fermi energy, the difference is that the bandgap is so wide that, as it says in the definition, there are not enough electrons in the conduction band at room temperature to allow appreciable current to flow. So, I guess that means that I was half right; the distinction between semiconductor and insulator is somewhat arbitrary. (It comes down to that phrase "appreciable current flow"). But you are right, there is a clear distinction between conductor and semiconductor.


 * Also I don't think that saying that the mobile charge carriers coming from dopants defines a semiconductor. It does define either an n-type or a p-type semiconductor, depending on the dopant species. But what about intrinsic silicon? Is that not also a semiconductor?


 * I'm trying to define things dynamically; based on "response to a change" rather than statically; based on "what it is." For a material we can ask what would happen if we take an ultra-pure sample and add tiny amounts of various impurities.  If the material is a semiconductor, then certain impurities will create mobile charges.  If the material is an insulator, then the impurities will only donate trapped and immobile charges.  If the material is a conductor, then large numbers of mobile charges are present even in the pure material.  Also, to be "semiconducting" the doping density which produces usable conductivity must be very small.  That way the cloud of dopant-produced carriers acts like an easily compressed gas, and the voltages needed to create a depletion zone are easily reached by simple power supplies (try calculating the gate voltage required to sweep all the charges from an FET channel made of copper.  Yeesh!) --Wjbeaty 09:31, Apr 19, 2005 (UTC)


 * As for immobile charge carriers, every solid is made up of (mostly) "immobile" charge carriers. All those protons and electrons that make up the atoms which make up the solid are "charge carriers"; that is, they carry either a positive or negative charge. So I don't think that path helps us to define a semiconductor. The points of distinction from conductors and insulators are mid band-gap Fermi level, and width of the band-gap respectively.darkside2010 12:39, 18 Apr 2005 (UTC)
 * But in semiconductor physics, the term "charge carriers" always implies current; a "carrier" is a mobile charge, not just a carrier of charge. (Sometimes they call them "current carriers," yet there's no such substance as "current," so the term "charge carrier" would be a bit less misleading to newbies.)   Don't lose sight of my original point: as a conductor, silicon is very much like vacuum: if we inject charges into it, those charges will be free to move.   But if we inject charges into an insulator (e.g. most plastics,) the charges won't move.  I've seen it explained like this: an insulator is full of "trapping centers" caused by lattice defects, and if we inject charges into the material, the charges will bond with the trapping centers and become highly localized.


 * PS, you'll probably notice that I'm pushing hard for classical-physics models as opposed to QM concepts. Is wikiP a textbook for grad students, or a reference for the general public?  Maybe QM is "more accurate," but if our goal is to inform the public, use of QM concepts is similar to use of Latin.  At the very least, we need to include concepts graspable by the general public, who are usually regarded as being at the level of intelligent 6th-graders.


 * Wj, I'm not even sure where to begin. Are you suggesting that we should dumb down the "sum of human knowledge" because it contains concepts which may not be readily understandable to sixth graders? There are some phenomena in this world which cannot be understood without the use of quantum mechanical concepts. The concepts themselves are not difficult to understand. For example, one does not need to be able to solve Schrödinger's equation to be able to understand that electrons in solids are allowed to occupy certain bands of energies and not others. I find your last paragraph particularly strange after reading the rant on distortion of information in physics texts on your homepage.


 * Sorry, I just don't agree that a semiconductor is like a vacuum. What is the permittivity of a vacuum (free space)? Of silicon? I can't find the values on wikipedia, but I'm hoping that one day I can. The point is that they are not the same. (And what is the analogue of a "hole" in free space?) Even the effective mass of electrons is not the same in a vacuum and a semiconductor.


 * Earlier you asked what happens if we put an electron deep inside an insulator (resin). How are we going to put the electron there? The point is, we cannot put an electron deep inside an insulator. Why? Because current does not flow in an insulator.


 * Did you miss my question about intrinsic semiconductors? A semiconductor is not a semiconductor because it has dopants which produce mobile charge carriers (although, this effect is often used, see p-type and n-type). Intrinsic silicon is a semiconductor, even if it is 100% pure. When we introduce dopants, we are actually introducing trapping centres. So your idea to define a semiconductor based on presence or lack of trapping centres is simply wrong (and self-contradictory). Sorry.darkside2010 11:22, 19 Apr 2005 (UTC)

1st semiconductor devices and related controversy
The semiconductor devices ruling the market but its first use represents a controversy.The controversy is that one of its 1st use was done by Indian Physicist Sir Jagadish Chandra Bose(30th Nov 1858-23rd Nov 1937). He ist used the device as a crystal detector in the wave receiver which he created. Moreover he had created a transmitter which could transmit waves as short as 4 mm on the year 1895. He excelled everybody of his time in designing a transmitter and a reciever with a crystal detector. The device was carried to Liverpool and was given a demonstation before The British Association. Due to this contribution he was knighted. His contribution was not given due prominence. until 100 years after his discovery. Discussion initiated by Somnath Majumder

 contact me x_planet_ocean_monster@hotmail.com

Should semiconductor device be merged with semiconductor?
This section inserted as a place to start the discussion about the suggested merge. The first discussion point can replace these two sentences. DFH 17:50, 27 September 2005 (UTC)


 * This proposed merge is currently under discussion on the WikiProject:Electronics project page. Please place all comments there Thanks--Light current 22:47, 27 September 2005 (UTC)

Thanks to Snafflekid for a thourough kleen up job! I think the two articles can now exist side by side with the disamb notes at the top. Progress should be noted on WikiProject Electronics page.--Light current 16:42, 1 October 2005 (UTC)

Proposed mergers: Electron-hole pair and Carrier generation and recombination
I proposed two mergers because
 * Both of the proposed merge-ins are mere stubs.
 * Neither contains any information that isn't appropriate here.
 * Neither is being actively edited to increase content.
 * The two proposed merge-ins are redundant -- they overlap each other very heavily.
 * This article would be improved by adding the contents of those two articles.

If there are no objections I will commit the merger within a couple of days. -- The Photon 05:58, 23 January 2006 (UTC)

Root and branch
The recent edits have made the page fairly unattractive, and the Root page/branch page concept doesn't really fit well here. Should Semiconductor be a branch from Electronics, or from Material science or from Solid-state physics or Metallurgy or Good (economics) or Chemistry or Mineral or ...?

Trying to get everyone to agree to a single classification of everything is the path to madness --- see the justification for the Categorization scheme.

And breaking up each article into multiple articles for each place it might fit into the root/branch hierarchy is not the answer. What was done to Waveguide just turned one stub article into four useless stub pages, one of which will probably never become a real article (Waveguide (acoustics)), and two of which (Waveguide (electromagnetism) and Waveguide (optics)) overlap immensely since one is just a special case of the other. Trying to do that with Semiconductor would mean breaking the article up into so many pieces that there wouldn't be one place to go if you wanted to actually know what there is to know about semiconductors.

So please use the root and branch scheme where it is appropriate --- but not pages like this that cover a wide territory on their own.

-- The Photon 05:49, 28 February 2006 (UTC)

Mistake
This part shown below is wrong or can be misunderstood. Can somebody correct it, thanks.

"The dopant atom accepts an electron, causing the loss of one bond from the neighboring atom and resulting in the formation of a "hole". Each hole is associated with a nearby negative-charged dopant ion, and the semiconductor remains electrically neutral as a whole. However, once each hole has wandered away into the lattice, one proton in the atom at the hole's location will be "exposed" and no longer cancelled by an electron."

Thoms --130.238.41.162 06:59, 24 May 2006 (UTC)

Didactic patter
This is supposed to be an encyclopedia article, not notes for a science lesson. There's too much what I call "didactic patter" in some sections of the article. Phrases such is "Note that " and "You would think that ". I just removed one glaringly annoying "It is interesting to note that ", yet the page still needs a further cleanup as regards the use of English. DFH 20:39, 28 August 2006 (UTC)

Rewrite or delete
This paragraph needs to be rewritten or deleted:
 * How semiconductors work is a direct result of quantum physics, in particular the Pauli exclusion principle. This principle states that no two fermions can exist in the same state at the same time. Electrons and holes both behave in this way, and the entire electron-hole state is forced to follow certain energy distribution statistics, which basically mean that at any given temperature the distribution of free electrons and holes are statistically determined and predictable. This also means that the conductivity of a semiconductor has a heavy temperature dependency, as a semiconductor operating at very low temperatures (-100°C or so) will have significantly fewer available free electrons and holes able to do the work. If you cool an IC down cold enough, the semiconductor will go intrinsic and all electrical signals will stop. (You would think that heating up the semiconductor has the opposite effect, but there are lots of other problems that happen at high temperatures, including loss of semiconducting properties due to too much free energy, so there is always a happy middle where the semiconductor wants to play!)

DFH 20:46, 28 August 2006 (UTC)
 * I have just removed the last two sentences from the above paragraph, which had particularly poor style, not up to the quality standard for Wikipedia. DFH 12:19, 29 August 2006 (UTC)

High and low temperature semiconductors
The article could do with new sections on High temperature semiconductors and Low temperature semiconductors. Some parts of the article are biased towards silicon as the material. DFH 12:04, 29 August 2006 (UTC)


 * That seems to be more applicable to device operational temperature range than anything else. Semiconductors don't fundamentally change just because of temperature (okay, throwing out VERY high temperatures where it ceases to be a solid).  Of course, carrier concentration is very much linked with temperature and the particular material.  This should definitely be discussed in this article, but it isn't cause for more article proliferation.  There's already enough fragmentation in the semiconductor physics pages. -- uberpenguin

Mobility
Lacking from the article is any description of the mobility of charge carriers, and the fact that electron mobility and hole mobility are usually different. DFH 12:08, 29 August 2006 (UTC)

Todo

 * Rewrite the physics section somewhat for clarity and accessibility.
 * Explain the relationship between carrier concentration and temperature a little better
 * explain the term degenerate doping. (done)
 * Talk a little about the Boltzmann approximation used to simplify the Fermi function-DoS product into a non-transcendental equation and its validity (especially as it relates to degenerate doping)
 * Finish the carrier concentration section
 * Add lots of decent pictures/illustrations:
 * Better band structure diagram
 * 2D atomic bond model explaining electron/hole carrier concept
 * Nice diagram of typical E-k band structure to illustrate how energy states vary with a particle's wave vector
 * A pretty photo or two... Maybe I'll find them, maybe I'll take them myself...
 * Make the examples less silicon-centric. I'll probably keep using silicon while I'm writing and go back later to mix things up with GaAs and some of the wide- and narrow-bandgap semiconductors.
 * comment: silicon-centric is the right thing to do. The world of semiconductors is silicon-centric. Probably there should even be a section explaining why. (The Photon)
 * Let me rephrase, I think it's a good idea to avoid using silicon for every example because it might suggest that silicon is the only important semiconductor. Of course silicon is the most important semiconductor currently because of its advantages for digital VLSI, but that's becoming less and less the case. -- mattb


 * Add a big section on carrier transport mechanics (obviously this will be highly summarized since full articles exist for most of these topics):
 * Mobility
 * Drift
 * Diffusion
 * Einstein relation (kinetic theory)
 * Band bending
 * Carrier generation and recombination
 * Thermal (band-to-band)
 * Indirect (R-G center) and related defects
 * Auger and impact ionization
 * Minority carrier lifetime and diffusion length
 * Photo R-G and direct/indirect bandgaps
 * Somehow, the term lattice constant needs to be linked. There's more to semiconductors than just band structure. (done)
 * History of the development of physical understanding of semiconductors (as opposed to the development of devices).
 * History of the development of semiconductor refining.
 * Economic importance of semiconductors (in raw or refined form, up to the level of unprocessed wafers, but not including ICs or other devices).
 * Any applications of semiconductors outside of electronics? What were they used for before 1947?

Lot of work, anyone looking on, do feel free to chip in and help or at least offer your comments if you think I've missed something. -- uberpenguin


 * Improve the semi-insulator section, or give it its own stub. --Sohaibafzal (talk) 06:41, 14 August 2009 (UTC)

some major edits to the beginning
Tried to focus the beginning on the commercial/technological importance of semiconductors and on a simple understanding of how they work, to motivate the rest of the article. --Rmalloy 18:35, 2 October 2006 (UTC)

Electrons available in the conduction band
"Semiconductors and insulators are distinguished from metals because the valence band in the semiconductor materials is very nearly full under usual operating conditions, thus causing more electrons to be available in the conduction band."

Should this be "causing less (or no) electrons to be available in the conduction band"? I'm assuming electrons in the conduction band increase conductivity, so "semiconductors and insulators" should "under usual operating conditions" have less electrons in the conduction band. Or am I completely misunderstanding this? —Preceding unsigned comment added by Rodent99 (talk • contribs) 04:22, 12 September 2007 (UTC)

Small error in paragraph 1
This isn't especially relevant, but in the first paragraph, all the examples of devices with solid-state electronics are (at least from what I know) technically computers. Let's use CD players as an example. It's true that you can't play video games on a Discmantm, I think, but they do use ICs and read digital optical discs. Even the cheapest ones have at least enough RAM for 45 seconds of buffered sound, an 80-track playlist, whether or not the gadget is in "hold" mode or if it has bass boost turned on, what the current volume, level of battery charge, radio station (if applicable,) and audo format is, what position the laser should be at (at level of precision on the order of more than 4.5 million possible positions per inch,) and how fast the disk should rotate (a range of 200 to 500 RPM, down to who knows how many decimal places,) plus whatever other data is required by internal processes. In addition, there must be enough processor power to control all of these processes, decode MP3 files, display stuff on the LCD, and randomly shuffle between tracks, to name a just a few required functions. Then there should be enough internal static ROM to store instructions, what letters to display where on the LCD, etc. While it's true that this is all firmware, it still computes things which is the definition of a computer.

Thus, "Examples range from computers to cellular phones to digital audio players," should read "Examples include nearly all computers, from PCs to cellular phones to digital audio players." —Preceding unsigned comment added by 67.180.200.204 (talk) 00:39, 2 October 2007 (UTC)

Page Rendering Issues
The band structure section with all the graphics is rendering badly in Firefox (2.0.0.11) on WinXP. Text and graphics are overlapping badly.
 * Yes - I found it goes away if the browser window is wide enough (also using Firefox and XP). --Wtshymanski (talk) 16:15, 30 January 2008 (UTC)

Where does it come from?
I can't find a single mention in any of these articles about where the silicon comes from. Perhaps this isn't the right article to mention this, but none of the others I linked out to said anything either. I assume "ultrapure silicon" isn't available and that some feedstock is used and purified. But what? And from where? Maury 13:13, 7 November 2007 (UTC)


 * Sand. Dicklyon 18:26, 7 November 2007 (UTC)

Namespace consistency issue(s)?
I realize the namespace for this article is pretty non-controversial as it stands. But I have a question. Currently, Electrical conductor and Insulator (electrical) are inconsistently named, and I have proposed on their talk page to bring them into some kind of consistency with each other. Either Conductor (Electrical) and Insulator (electrical) or else Electrical conductor and Electrical insulator, might be appropriate. However, I then realized that Semiconductor is midway between these two extremes, and may benefit from a similar namespace consistency push. So, I'm wondering what the precedent might be for such a thing. If the three were to be brought into line with each other's naming convention(s), then the namespace on this page might change to Semiconductor (electrical) or Electrical semiconductor. I'm in favor of the former. But I don't know if changing the namespace would be acceptable or not (assuming a name change would also include a redirect from the original name(s) to the updated article so people can still find them), so I figured I'd put it out there for regular contributor to this and/or the other articles to decide amongst themselves. Not sure what the best way to go about it is. For consistency, I'd say that Conductor (electrical), Semiconductor (electrical) and Insulator (electrical) would be the most sensible arrangement (in my off-the-cuff opinion), when thinking in terms of disambiguation pages already in use (such as the one for Conductor (disambiguation)). Talk amongst yourselves. Mgmirkin (talk) 07:37, 17 May 2008 (UTC)


 * There's no reason to mess with semiconductor, since there's no alternative to the electrical/electronic kind. As for the others, it doesn't much matter, since we have no particular need for consistency, but you could propose one change or the other on the relevant page if you think that would be an improvement. Dicklyon (talk) 22:41, 17 May 2008 (UTC)

Applications
This is a decent summary of the theory behind semiconductors, but someone knowledgeable needs to add more information about the applications of semiconductors. Further, there is no mention of why semiconductors make good candidates for these applications. Reading this article doesn't leave the reader with an idea of the huge importance of semiconductors, nor what it is about semiconductors that make them so important. PowerWill500 (talk • contribs) 21:11, 24 November 2008 (UTC)
 * A discussion of applications would be like a discussion of the applications of air. Better to reference the various semiconductor devices and put the applications there.
 * What I think the article needs is some *history* - right now it's no better than cribbing the intro to some textbook, dumping a bunch of facts as if they were Revealed Truth or a gift of the saucer people. How did we get to semiconductors? What were the first devices?  What was the first clue about semiconductor behavior? There's more than 100 years of history to cover, going back to cat's whiskers and selenium cells... --Wtshymanski (talk) 14:54, 25 November 2008 (UTC)


 * I'll agree with that. The article should at least illustrate why semiconductors are so useful, though. Instead of just listing the properties of the semiconductor, the article could briefly discuss what it is about said properties that are desirable for various applications. PowerWill500 (talk) 20:53, 6 December 2008 (UTC)
 * I agree both that we need more information on history and applications. See also semiconductor device; revisiting the merge question may be in order. -- phoebe / (talk to me) 23:33, 6 April 2009 (UTC)

Breaking up the image gallery
The image gallery near the beginning of the article should be broken up. I read it and didn't quite understand its theme. An encyclopedia article should not be a slide show if a more ordinary interlay of text and images can communicate more clearly.

I suggest that the first few images be dropped altogether, and the later ones dispersed through the article. I'm not sure how exactly to do this. If any of you have specific ideas, please comment here. Crystal whacker (talk) 17:40, 7 January 2009 (UTC)

Wrong Definiton
The first line of the article quoted below is an incorrect definition.

A semiconductor is a material that has a resistivity value between that of a conductor and an insulator.

The resistance of semiconductors is an irrelevant fact. Which conductors and which insulators is it talking about? At what temperature? Does is mean that if an alloy “has a resistivity value between that of a conductor and an insulator” it is automatically a semiconductor?

In fact, pure semiconductors at the normal temperature range have high resistance and act as insulators in the chips.

A much better definition (though not perfect) would be:

Substance whose conductivity is poor at low temperatures but is improved by minute additions of certain substances or by the application of heat, light, or voltage: used in transistors, rectifiers, comuter chips and other electronic devices. Artakka (talk) 20:30, 6 July 2009 (UTC)


 * Agree. Why don't you edit it? -- Sohaibafzal (talk) 06:45, 14 August 2009 (UTC)
 * Semiconductors originally became so-called because of that property. The difference in conductivity between common conductors and common insulators is very great, a minimum of around 15 orders of magnitude. By comparison, common conducting materials fall in a range of electrical conductivity of perhaps 4 orders of magnitude. Common insulators vary somewhat more widely, but still only around 6 orders of magnitude. It was therefore natural to classify materials as conductors or insulators. As always, the exceptions are interesting, and semiconductors are no exception! Early studies were difficult because the significance of very low levels of impurity were not well recognised, nor were the significance of crystal boundaries and surface effects, so widely varying values were observed in what appeared to be 'pure' samples that were apparently identical. It remains the case that most semiconductors fall in a range of conductivity between 10^3 S/cm and 10^-8 S/cm while conductors and insulators fall outside this range. In particular even pure silicon is a much better conductor than glass, which is a relatively poor insulator. Silicon functions as an insulator in chips only because its conductivity is poor relative to adjacent doped material. Where real insulation is required in chips diode junctions or other materials, often silicon dioxide, are used. The definition suggested is poor because it doesn't define 'low temperatures' and some semiconductors have relatively good electrical conductivity at relatively low temperatures, say around room temperature. Nor are all semiconductors sensitive to low levels of impurity. I suggest that the definition be changed to something like 'A semiconductor is a material that has a conductivity in the range 10^3 Siemens/cm and 10^-8 S/cm, that is, between that of a conductor and an insulator'. However there is a bigger problem.


 * The first sentence of the article refers to solids and to control of conductivity by the addition of impurities. Liquid semiconductors have been around for at least 50 years. They share with better known semiconductors intermediate conductivity and a rapid variation of conductivity with temperature but lacking the rigid crystalline structure of conventional semiconductors such as silicon they are relatively insensitive to impurities and radiation damage. Note that low temperatures do not change this, because liquid semiconductors may become glassy rather than crystallising. The first sentence should be deleted. treesmill (talk) 14:55, 9 October 2009 (UTC)


 * I'm coming to this way late, but I've generally not seen semiconductors defined the way they are in this article. It's always been in terms of the band gap. Semiconductors may happen to have these intermediate conductivities, but that is not what makes them semiconductors. The definition suggested by Artakka, whatever its flaws, seems much better to me than the current text. I won't immediately edit, but can anyone point to a reliable source (ie a textbook) defining semiconductors as "a material that has an electrical conductivity between that of a conductor and an insulator"? I've got two textbooks here that define it in terms of band gap but that might just be because my background is in solid state physics. Gruntler (talk) 12:20, 3 January 2010 (UTC)


 * I've only just noticed this. Semiconductors are defined by their properties. The band gap is part of a model in which a complex set of electronic properties are visualised in a particularly simple and effective way. The model helps to explain the properties of conductors, semiconductors and insulators, but it is still a model. See above for more detail. treesmill (talk) 07:47, 16 June 2010 (UTC)

"Delocalized Orbits"
The article states: "Putting two atoms together leads to delocalized orbits across two atoms, yielding a covalent bond." This is a contradiction - from the delocalized electron article, "In chemistry delocalized electrons are electrons in a molecule that are not associated with a single atom or to a covalent bond."

Therefore, either the bond is covalent, and the orbit is not delocalized, or the orbit is delocalized, and it does not form a covalent bond. The former seems to be the correct case here...someone please make the appropriate change. 71.141.233.119 (talk) 01:17, 7 January 2010 (UTC)
 * You pointed to a terminology trick: delocalized electrons are electrons in solid which don't "belong" to any individual atom anymore. Delocalized orbitals are those which are less localized than the orbitals of an isolated atom; they can be even shared by more than one (two) atoms. Thus it is all about the degree of delocalization. Materialscientist (talk) 01:26, 7 January 2010 (UTC)

Active devices
The mention of active devices at the start of the article is incorrect. A thermistor may be made of a semiconductor and its properties are affected by temperature but it is not an active device. The sentence 'Such a compound is known as an "active" device.' is strangely phrased since an active device is not a compound even though it may be made from compounds. The next sentence doesn't need the word 'active' at the start, it is even more correct without it. In any case if mention is to be made of active devices it belongs later in the article. I have made these changes. treesmill (talk) 16:11, 4 July 2010 (UTC)

Lead Rewrite Needed
I think the lead here isn't as clear as it should be. It manifests one of the Wikipedia pitfalls, namely disjointed writing, as may happen when multiple authors contribute piecemeal. Further, it doesn't give a clear picture to the general audience. I think it's too technical.

Bottom line is I went to this page to learn what semiconductors are and I came away not knowing.

Then I read this page: "Wikipedia:Make technical articles understandable" ...and came away believing the page on Semiconductors doesn't meet the criteria.

Is there a good writer out there who knows the topic and might comb through the lead and make it better? Jaywuz (talk) 20:49, 6 August 2011 (UTC)

Amen to this, this page is worthless to 90% of people searching on semiconductors. I feel the same, I came here to learn what a semiconductor does and that issue is not addressed in this article. It should be the first paragraph. This article is just techno ramble. — Preceding unsigned comment added by 184.99.139.213 (talk) 06:46, 29 August 2011 (UTC)

Article is almost incoherent - revise or rewrite?
As it stands this article is mostly useless to its intended audience. I would suggest that it is only comprehensible to people who already have an advanced understanding of semiconductor physics.


 * The lead, which should offer a brief and approachable overview of the subject, is neither brief nor approachable, and fails to summarize the rest of the article.
 * The "Explaining semiconductor energy bands" section states that "There are three popular ways to classify the electronic structure of a crystal". This is the only part of the section that I, as a science-educated general reader, understood. And even that was confusing, since it only seems to discuss one way, not three, and if it's a way to "classify the electronic structure of a crystal" it's not obvious how.
 * The rest of the text is impossibly dense. Yes, by and large, wikilinks are provided to the relevant background articles, so if I spent a year or two researching quantum physics, the Pauli exclusion principle, and Fermi-Dirac Statistics, then I might be qualified to attempt to understand the first two main body paragraphs.
 * But then the third would tell me that "In the preceding description an important fact is ignored for the sake of simplicity." Jesus wept!

Now don't get me wrong, I do understand that some things are Actually Hard (tm) and that this topic is one of them. But all the same, we have a nearly-useless article which completely fails to:


 * offer an approachable introduction for general readers
 * summarize in a simple way the science it depends on, providing the reader with at least the bare minimum take-home points
 * describe applications in any depth

Now it's obvious that this article has been in approximately this state since Ancient Days. The question to my mind is whether by hard graft and much suffering we can add a useful lead, convert the current one into a more expansive introduction, throw out whatever quantum physics that isn't absolutely necessary to understanding semiconductors, aggressively summarize the rest, and generally make the whole thing accessible to the kind of person who might want to look up "semiconductor" on Wikipedia. Or, would it be easier to start from a blank page?

Thparkth (talk) 01:02, 27 October 2011 (UTC)
 * Go for it.. Though it must say something that membership in all those projects has not brought this article to FA status. I feel better about reverting bot project tagging of articles with peripherally relevant projects; if "semiconductor" isn't core to electronics, I don't know what is. --Wtshymanski (talk) 15:24, 27 October 2011 (UTC)

Usage and significance?
I came to this article from the article on Transistors, which mentions semiconductors in the first paragraph. I wanted to know why semiconducters are used in transistors, and what special useful properties they have. Why do we care so much about them? Apart from "a conductivity level between that of insulators and conductors" I found no information to answer my question. Please add this to the introduction of the article. Something like this, from the article on Semiconductor Devices:

"The main reason semiconductor materials are so useful is that the behavior of a semiconductor can be easily manipulated by the addition of impurities, known as doping. Semiconductor conductivity can be controlled by introduction of an electric or magnetic field, by exposure to light or heat, or by mechanical deformation of a doped monocrystalline grid"

(I think special properties and usage should be part of the article about a material. For instance, the article on concrete gives information about properties and usage. Readers don't have to go to a "concrete devices" article to figure those things out.) — Preceding unsigned comment added by 67.186.35.251 (talk) 01:41, 15 January 2012 (UTC)

Edit: Yeah, okay, I fail at reading. The section on doping states that this is their most useful property. It would be a very good idea to put this fact prominently in the introduction. I wanted to get a basic idea of semiconductors, and I stopped reading once I saw a formula and once the section titles stopped using words which I knew. — Preceding unsigned comment added by 67.186.35.251 (talk) 01:49, 15 January 2012 (UTC)

History of semiconductors
Shouldn't there be a section on the history of semiconductors? Who discovered them, their various applications, etc? Possibly an article of its own! W 17:32, 20 January 2007 (UTC)
 * I see uberpenguin mentioned it in his todo list. Guess this is a vote of approval and suggestion of focus.W 17:36, 20 January 2007 (UTC)
 * copper oxide rectifiers, and selenium rectifiers, trace back at least to the 1930's. some FET transistors were made in about 1930, but they were very primitive and quite slow.  one was 1 cycle per second, very slow.  Bob Emmett (talk) 06:34, 19 March 2010 (UTC)
 * But how old were first experimental semiconductor diodes? How about light dependent resistors? 213.141.100.28 (talk) 09:25, 25 March 2011 (UTC)
 * A year later...I've tried to give a thumbnail history (really, more of a chronology) but eventually this will have to spin off to its own article; there's all kinds of interaction between theory and practice that needs to be described. We wouldn't have semiconductors without quantum mechanics, and I wonder if we wouldn't have had quantum mechanics without semiconductors. --Wtshymanski (talk) 15:10, 7 August 2012 (UTC)

The lead
A semiconductor is a material with electrical conductivity intermediate in magnitude between that of a conductor and an insulator.

Does that even mean anything? Surely a better word for such material would be... a resistor? I am a mere Geologist so forgive me if my basic knowledge of this topic is wrong, but wouldn't it be more accurate (and more useful) to say something like:

A semiconductor is a material which can behave like a conductor, or like an insulator, depending on the prevailing circumstances.

Thparkth (talk) 02:48, 20 April 2012 (UTC)
 * I do have some sympathy with previous editors, who have clearly put a lot of work into this article. The basic problem is that the science behind crystalline semiconductor operation is extremely difficult for non-physicists to grasp. As a comparison, it's possible to explain vacuum tube operation in terms of electrons boiling off a hot cathode and being attracted to a charged anode. This isn't actually what happens but it's a reasonable approximation which most people can easily understand. Semiconductor physics can only be meaningfully explained in terms of electron energy bands and the like. I also find the article difficult, but I don't have a solution, other than to summarise it as 'a sort of magic'. --Ef80 (talk) 14:08, 21 May 2012 (UTC)

The grammar doesn't even make sense. — Preceding unsigned comment added by 81.102.246.0 (talk) 06:28, 17 August 2012 (UTC)

Suggest merge
Aren't N-type semiconductor and P-type semiconductor redundant with this article? The latter is virtually a dictionary definition and stuby; the former recaps all the band theory which is already here. --Wtshymanski (talk) 15:19, 30 July 2012 (UTC)


 * Support - By rights, the articles N-type semiconductor and P-type semiconductor should be virtual clones of each other and Semiconductor should contain much of the same information. This can all usefully be distilled into one article.  I added the  tags to this article for you - something which you seem determined not to do for some reason.  Now let's see if you can add all the appropriate maintenance tags to the merged articles when you merge them. DieSwartzPunkt (talk) 13:15, 26 October 2012 (UTC)

i cant find manufacturing of semiconductors based on moore's law.
Ram nareshji (talk) 08:30, 6 December 2012 (UTC) i cant find manufacturing of semiconductors are based on moore's law in this article. pls add