Talk:Silicon carbide

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Contents

[edit] Stubbed due to copyright infringement (2003)

Removed possible copyright infringement. Text that was previously posted here is the same as text from this webpage:

http://www.shinagawa.co.jp/English/Products/index1.html

—This unsigned comment was added by Sannse (talk • contribs) on 19:11, 11 May 2003.

[edit] Semiconductor properties

I've moved the following text from the article here, to be edited for tone and checked for accuracy:

The primary application of silicon carbide would be in high power semiconductor switches like power MOSFET or IGBT. Higher breakdown electric field and thermal stability of SiC promise to result in much superior properties in terms of high temperature, high frequency operation of power electronics systems based upon SiC devices.

One of my concerns is with "would be" and "promise to result in". This suggests that these are not things that are currently documented as fact (i.e., they may not be encyclopedic). High temperature operation is well documented and already mentioned in the text, so mentioning it here is redundant. High frequency operation should be documented somewhere, which means it can be checked. The "breakdown electric field" line puzzles me, as you'd care about breakdown field for the dielectrics used in the fabrication process, not the semiconductor itself. "Thermal stability" is ambiguous as a term, as well.

A comparison of SiC's properties to those of silicon, SiGe, GaAs, and so forth would be useful, but that would be better placed on the semiconductor page.

--Christopher Thomas 6 July 2005 19:29 (UTC)

Yes, the structure of SiC itself "breaks down" at high electric fields. See e.g. (Nature materials):
For instance, in high-power bipolar devices, there is a degradation in the material's electrical properties that seems to be related to the development of extended stacking faults, originating from in-plane dislocations in the SiC.
I'm moving the text in question back.
--Larssl (talk) 14:29, 28 April 2008 (UTC)
I would suggest the Wide bandgap semiconductors page. --ArséniureDeGallium 11:45, 21 December 2005 (UTC)
Maybe related to this press release: http://www.cree.com/News/news232.asp - also Cree seems to have some Navy contracts for phased array radar using these devices. --Pjacobi July 6, 2005 20:24 (UTC)

I don't believe the energy gap of any form of SiC to be as low as 1.96eV. See http://www.ioffe.ru/SVA/NSM/Semicond/SiC/bandstr.html Jaraalbe 22:47, 15 December 2005 (UTC)

[edit] "Discovery" of Moissanite?

Just curious to note that while this page lists Acheson as the discoverer, other sites list Dr. Moissan in 1893 as the one who discovered the material. These include:

I'm just a layman, and am not implying anything about the relative levels of scholarship among these sites. However, as a reader I would be more inclined to respect and accept this article's content if it were to at least acknowledge that an argument (mistake? misunderstanding?) simply exists.

Just my $.02..... —The preceding unsigned comment was added by 69.180.3.55 (talk • contribs) on 02:43, 19 April 2006.

The material silicon carbide was created/synthesized by Acheson in 1893 and the naturally occuring form, the mineral moissanite, was discovered in 1905 by Moissan. It is very possible for materials to be "discovered" twice in this manner (like Technetium, which was falsely discovered in 1828, 1846, 1847, 1877, 1896, 1908, possibly created in 1927, definitely created in 1937, and later discovered naturally in 1962). --Splarka (rant) 00:20, 3 June 2006 (UTC)

Moissanite has been the target of a smear campaign for years and it appears that campaign has been extended to wikipedia. Wikipedia have conflicting information. In the wikipedia entry for Dr. Henri Moissan it clearly states that he identified silicon carbide within the meteorite particles in 1893. In 1905 Moissanite was named in his honor by a gemologist from Tiffany & Co. The Henri Moissan information also coincides with the information from the Charles & Colvard website. This is why Moissanite should have a separate entry in wikipedia and not be combined with Silicon Carbide as the crystalline form of SiC has different properties, uses, and discovery.

  • Could you please cite who is behind the "smear campaign" and what motivates them? Incidentally, I think that synthetic Moissanite used as a gemstone should have its own article, aside from SiC as an industrial material. T.E. Goodwin 05:57, 17 February 2007 (UTC)

Why is it that Cubic Zirconia (CZ) has a separate wiki entry and Moissanite does not? CZ is not redirected to Zirconium Oxide so why is Moissanite redirected to SiC? This clearly demonstrates the bias and mendacity that Moissanite endured even to the point that wikipedia is not a good reference for moissanite.

[edit] Good Article nomination has failed

The Good article nomination for Silicon carbide has failed, for the following reason:

There are several basic flaws. Most importantly there are no references. Also, the lead section does not provide a summary of the article's content at the moment, and links in section headings should be removed according to the manual of style. Headings are also incorrectly capitalised. Worldtraveller 23:44, 27 April 2006 (UTC)
I updated the manual of style. Maybe we can add more refrences and work on the intro. --Supercoop 16:21, 3 May 2006 (UTC)

Somebody, please help. I found the text almost verbatim on the uses of SiC at the following link: http://www.mdatechnology.net/techsearch.asp?articleid=174 and attempted to add it as a reference. The reference looks funny because I obviously don't know what I'm doing. I left the edit in because I thought the text should be attributed, I hope I didn't mess things up 70.95.149.247 08:19, 23 October 2007 (UTC)Jay Abel

[edit] Anon contribution

The following text was added by 59.182.39.56 (talk • contribs):

Silicon Carbide technically known as carborundum is an extremely hard, infusible, thermally stable and chemically inert solid. The structure of Silicon Carbide is similar to that of Diamond, if alternate Carbon atoms in the diamond molecule are replace by Silicon atoms, what we get is the tetrahedral structure of Silicon Carbide. Hence, it is extremely hard, used as an abrasive and finds special place in application of disc brakes especially the Porsche Carrera GT mentioned above. In addition to this, it is likely to mention that Boron Carbide B4C is better than SiC in respect to abrasiveness. However, its manufacturing difficulty makes it unfeasible for industrial applications inspite of its complex crystal lattice.

The first two sentences are setting off my "this might be copied from somewhere" alarms, but it's possible anon is just a good writer. This is in completely the wrong part of the article, and duplicates some of the article information, so I've moved it here for review/re-merge. --Christopher Thomas 19:28, 6 July 2006 (UTC)

[edit] Moissanite Jewelry FAQ

This external link is for Joy Jewelers of Los Angeles, an obviously commercial retail website. While there is some information provided concerning the use of SiC as a diamond simulant, the overall content is overwhelmingly retail in nature. Does anyone else concur that this link should be eliminated? T.E. Goodwin 05:28, 2 August 2006 (UTC)

I agree entirely, so I have just removed the link. DFH 16:29, 29 August 2006 (UTC)

[edit] Band gaps

I just changed the two values quoted as the band gaps for SiC to be the same as they are on the band gap article. DFH 16:24, 29 August 2006 (UTC)

[edit] Confusing paragraph in 4.10: Uses - As a Jewel

I am confused by the paragraph below. My comments are in (bold italic) to explain where I'm confused.

Simulated moissanite is somewhat harder than common cubic zirconia (9.0 vs. 8 1/2), lighter (SG 3.33 vs. 5.6), and much more resistant to heat. The newer Russian simulants (I'm assuming the "newer Russian simulants" are CZs?), for example Russian Star, are equal to or have a greater hardness than simulated moissanite (This is contradicts the original statement of moissanite being harder than CZs. So is this saying that the newer Russian simulants (which I'm assuming are CZs) are harder than the older CZs and even harder than moissanite?). This ("This"? The hardness of the newer Russian simulants? Define what "this" is.) results in a stone of higher lustre, sharper facets and good resilience (somewhere the subject is getting lost. Are we talking about the newer Russian simulants still or did we change back to moissanites. I'm assuming we're back to moissanites, but if that's what is intended, the way it is written is incorrect.) : (Why a colon here? How is the former connected to the latter part of this sentence?) loose simulated moissanites may be placed directly into ring moulds, as the synthetic stones remain undamaged by temperatures up to twice the 900 °C melting point of 18k gold.

Here is the paragraph as it appears on the article page so it can be read without my interruptions:

Simulated moissanite is somewhat harder than common cubic zirconia (9.0 vs. 8 1/2), lighter (SG 3.33 vs. 5.6), and much more resistant to heat. The newer Russian simulants, for example Russian Star, are equal to or have a greater hardness than simulated moissanite. This results in a stone of higher lustre, sharper facets and good resilience: loose simulated moissanites may be placed directly into ring moulds, as the synthetic stones remain undamaged by temperatures up to twice the 900 °C melting point of 18k gold.

I am not qualified to make any changes to this paragraph because I truly do not know what is or is not correct. I came here to learn about moissanites. If anyone who knows about moissanites could please clarify that section, I would appreciate it.

The paragraph in the block quote has a number of fallacies. Moissanite is second in hardness to a diamond on the Mohs scale at 9 1/4. Also moissanite is not only lighter to CZ it is also lighter than a diamond. Also Moissanite has never been marketed nor offered to the public by its sole source producer -- Charles & Colvard -- as a diamond simulant. Describing moissanite as a "diamond simulant" is a pejorative designed to diminish the jewel in the mind of consumers by put it into the same class as CZ. Moissanite is a separate category of jewel and all you have to do is look at its properties to see that moissanite has more fire, brilliance, and luster than a diamond. Moissanite cannot hardly be described as a diamond simulant since a diamond itself cannot outperform moissanite in those categories.

--24.242.211.107 20:02, 18 November 2006 (UTC)

[edit] NPOV thingy on comparison with diamond

In 1998, Charles & Colvard introduced gem-quality synthetic silicon carbide to the market under the name "moissanite". This gemstone possesses superior fire and brilliance to diamonds.

The second sentence... Does it sound like an opinion or an attempt to insert an advertisement to anyone else? I don't know a lot about gemstones, but "fire" and "brilliance" don't sound like scientific terms to me. I certainly have heard them on infomercials before, though. Is there is a more accurate way to describe the aesthetic differences between the two gemstones? Clarphimous 01:31, 13 June 2007 (UTC)


[edit] Missing Finnish (Suomi) link

Could someone make a link to the Finnish version? http://fi.wikipedia.org/wiki/Piikarbidi (pii=silicon, karbidi=carbide) --89.27.15.209 18:02, 11 September 2007 (UTC)

Done. --saimhe 19:31, 11 September 2007 (UTC)

[edit] Electrical conductivity & resistivity

Firstly, could people that don't know the difference (or relationship) between electrical conductivity and resistivity, please refrain from editing anything pertaining to this? Thanks.

I have asked for a citation (in the "Production" section) regarding both the prevalence of Nitrogen impurities in SiC, and the allegedly conductivity-reducing properties of iron and aluminium impurities. (Perhaps users "Bancquo" and 194.128.14.113 could oblige?)

Joe. —Preceding unsigned comment added by 61.8.13.206 (talk) 04:31, 30 January 2008 (UTC)

In fact, nitrogen is the most commonly used n-type dopant in SiC, whereas aluminium is the most commonly used p-type dopant. The statement
... these darker crystals are less pure and usually doped with nitrogen, which decreases the electrical conductivity of these samples, and with aluminium and/or iron, which increase conductivity.
is indeterminate in the way that it is now. It would be true, on the other hand, if the SiC in question was p-type from before. Then N doping would make it less p-type and therefore decrease the conductivity, whereas Al doping would increase the conductivity up to a certain point. But if the SiC was n-type from before, then more N doping would increase the conductivity and Al doping would decrease the conductivity. This should be clear simply by looking at the periodic table: Elements to the left of group 4 make SiC more p-type. Elements to the right of group 4 make SiC more n-type.
Something needs to be done with this confusing statement, and if no more information comes up then I will change it myself.
--Larssl (talk) 14:46, 28 April 2008 (UTC)

[edit] Fatigue

What long-term properties does silicon carbide have? I ask because I saw in The Clock of the Long Now:

Therefore, using a material that is known to just plain not change state and design completely around that is the way to go. His suggestions were silicon and silicon carbide. I expressed my reservations as to the brittleness of these materials and he said yes, of course they're brittle, but we'll know whether a Si part works for 10,000 years because it will catastrophically fail immediately if it doesn't work. If it doesn't fail on you immediately, well then there you are![1]

--Gwern (contribs) 18:05 25 April 2008 (GMT)