Silicene Discovered: Single-layer Silicon That Could Beat Graphene To Market 67
MrSeb writes "Numerous research groups around the world are reporting that they have created silicene, a one-atom-thick hexagonal mesh of silicon atoms — the silicon equivalent of graphene. You will have heard a lot about graphene, especially with regard to its truly wondrous electrical properties, but it has one rather major problem: It doesn't have a bandgap, which makes it very hard to integrate into existing semiconductor processes. Silicene, on the other hand, is theorized to have excellent electrical properties, while still being compatible with silicon-based electronics (abstract). For now, silicene has only been observed (with a scanning tunneling electron microscope), but the next step is to grow a silicene film on an insulating substrate so that its properties can be properly investigated."
Re:And now? (Score:5, Insightful)
None of those have the same crystal structure as carbon or silicon, which both form diamond lattices due to being group IV materials. As someone who works with silicon/gallium arsenide semiconductors and crystal formation, I think this is pretty exciting news. There's a large difference between observing something and making it work the way you want it to, though, so my guess is it'll be a while before silicene can be properly studied, let alone used in commercial semiconductor devices.
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I think you are confused
Learn to chemistry. It's the 4 valence behavior that both provides the familiar diamond geometry as well as allowing hex-rings with extremely low electron latency.
The part I'm more curious about is whether this kind of behavior can be applied to heavier elements that do not hold as tightly to their electrons. I doubt it, because I'm sure someone would've already noticed if tin or lead was an exceptionally good conductor. Still, few people expected carbon to be as capable a conductor as it is with certain
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Erm - it's *you* who should learn chemistry. If you believe that sp2 hybridized graphite (excellent conductor, very soft) and sp3 hybridized diamond (insulator, very hard) have similar properties just because it's the same group IV element, then - well... - sorry to say... - but you are full of shit.
And your senseless mumbo-jumbo on conductivity sadly just proves it.
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The fact that C and Si lie in the same group allows for the special bonding (think valence electrons and preferred oxidation states) that they have although Si might have the band gap that is needed that C doesn't. tocsy was referring to this. You don't see varied structures in Li or Na or K since they aren't like Carbon or Silicon.
Re:And now? (Score:4, Informative)
I apologize, I was hurried and didn't explain myself very well in the first post. You're correct, graphene (and apparently now silicene) has sp2 hybridization, but as the AC reply to your post suggests, it's the fact that carbon is group IV that gives it such interesting characteristics as a 2D structure. As a sidenote, I'd hesitate to assume silicene's electronic properties - silicon doesn't naturally form anything like graphite (i.e. stacks of loosely bonded monolayers) that I know of and since the properties of diamond and graphene are so different and I don't study monolayer materials, it'd be irresponsible of me to say "silicene will have X band gap" etc. Very interesting stuff, though, I'll be interested to see how this develops.
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It'll likely be manufactured under heavy vacuum, then sealed, and never exposed to any O2.
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he didn't say that graphene includes sp3 hybridized C atoms as in diamond. he said that both carbon and silicon form diamond lattices, which makes Si more similar to C than other elements like lithium, sodium etc. this is true. Si forms diamond cubic crystals.
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Plasticene?
Re:And now? (Score:5, Funny)
I'm still waiting on the atom-thick holographic film, Holocene(tm).
Re:And now? (Score:5, Funny)
And the flexible version.... Pliocene
Re:And now? (Score:5, Funny)
I'm waiting for the censored version of the Oxygen-Boron layer: OBscene.
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Toil onwards, nerds. I'll be hangin down at Starbucks with me iPhone, iPad, and Macbook Air as part of the self-referential Hipsterscene
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He wins, that's about as mono-layer as you can get!
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Mononucleiosis, maybe!
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But no one has asked the really important question. How do you pronounce silicene?
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Beat Graphene to Market? (Score:5, Interesting)
So, Silicene has just been observed for the first time under a scanning tunnel microscope, has had its properties only theoretically proposed, and is hoped to be "as miraculous as Graphene". Nevertheless, the author of the article already believes that it will beat Graphene to the market? Sheesh! Are all headlines nowadays conjured up by a dedicated company full of marketing types?
Re:Beat Graphene to Market? (Score:5, Funny)
Remember, "theorized to have" probably means something more like "we got some motherfuckin' mathematical models which say that this shit got all kindsa properties like".
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Remember, "theorized to have" probably means something more like "we got some motherfuckin' mathematical models which say that this shit got all kindsa properties like".
Is there a version of "theorized to have" without incest and fecal matter? I think I'd be more interested in those models.
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Nope.
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Are all headlines nowadays conjured up by a dedicated company full of marketing types?
Of course not. There are several companies in this thriving industry, each taking up a particular niche. There's one for the "everything's racist" stories, some for "mediocrity is amazing", a few for "this is the best/worst/biggest/smallest/oldest/newest thing ever (since that other one)", a couple whose shtick is "everything is interesting to nerds because it will change the world", and so on...
Guess which website you're on now?
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The challenges related to making graphene microelectronics are overwhelming. It may well never come to market. Silicon is great because because it's relatively cheap, and much easier to work with. Plus, all the fabrication techniques we use now work with silicon. So yes, if this technology would work at all it would almost certainly beat graphene to market. It would beat graphene out of the market entirely.
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The challenges with respect to silicen are even worse than for graphen. Silicen does not integrate with Si-electronics in any straight-forward way. Nor does any technology developed for Si-bulk apply to silicen. The handling of silicen is even more difficult than it is for graphen, as the scotch-type method does not work since there is no equivalent for graphit in the silicon world.
BTW, the material cost of a monolayer of graphen is not so much bigger than the one of silicen. Think of a pencil.
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The problem with graphene is that carbon doesn't have a band gap, making semiconductors difficult to say the least. Silicon does have a band gap (wich I am using right now, as it is the basis of modern computing.
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Physical Limits (Score:2)
Re:Physical Limits (Score:5, Funny)
"silicon â" a material which will probably reach its physical limits in the next 5-10 years" Haven't they been saying that since 1980?
Yes -- and therefore silicon has no physical limits and Moore's Law will continue forever.
Re:Physical Limits (Score:5, Interesting)
"silicon - a material which will probably reach its physical limits in the next 5-10 years" Haven't they been saying that since 1980?
Yes, there's been a lot of flawed assumptions but now we're nearing the most fundamental limits. The lattice spacing of silicon is about 0.55nm and the process size usually goes down with a factor about 0.6, so:
22 nm * 0.6 = 14 nm
14 nm * 0.6 = 8 nm
8 nm * 0.6 = 5 nm
5 nm * 0.6 = 3 nm
3 nm * 0.6 = 1.8 nm
1.8 nm * 0.6 = 1.08 nm
1.08 nm * 0.6 = 0.648 nm
Re:Physical Limits (Score:5, Insightful)
So late this decade or next decade at the latest Moore's law is dead.
Unless someone comes up with something clever again.
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Unless someone comes up with something clever again.
Well, apparently you can turn a single atom [abc.net.au] into a transistor but I don't really see anybody being able to do anything about the size of atoms. Perhaps you can do some other wizardry that'll give us terahertz processors or something but the transistor density won't get denser than this.
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So far every shrink reduced costs too, but the cost reduction may stop before shrinking stops. Smaller processes would then only be used due to higher performance, but would be more expensive. As a practical example, 28nm today is still more expensive than 40nm, an
A Si mono-layer will grow a natural oxide fast (Score:5, Interesting)
I would be a little concerned that the silicon mono-layer would grow a natural oxide very fast and thus consume the silicon?
The solution in a HEMT transistor is cool in this respect. It is using an un-doped IV-V semiconductor next to a highly doped layer and excess carriers will form a two-dimensional electron gas at the interface. The carriers will move along the surface of the un-doped semi-conducter that since it is un-doped have better mobility and fewer defects than doped material. It must be something along this property they try to re-create with a silicon mono-layer.
Stacked graphene (Score:2)
You are probably alluding to discovery that bi-layer or tri-layer graphene stacks can be induced to have a tunable bandgap... http://www.lbl.gov/msd/assets/docs/highlights/09-9FengWang_bilayer_graphene.pdf [lbl.gov]
Abstract from one of the reports (Score:4, Informative)
"Because of its unique physical properties, graphene, a 2D honeycomb arrangement of carbon atoms, has attracted tremendous attention. Silicene, the graphene equivalent for silicon, could follow this trend, opening new perspectives for applications, especially due to its compatibility with Si-based electronics. Silicene has been theoretically predicted as a buckled honeycomb arrangement of Si atoms and having an electronic dispersion resembling that of relativistic Dirac fermions. Here we provide compelling evidence, from both structural and electronic properties, for the synthesis of epitaxial silicene sheets on a silver (111) substrate, through the combination of scanning tunneling microscopy and angular-resolved photoemission spectroscopy in conjunction with calculations based on density functional theory."
This is from Phys Rev Letters (DOI: 10.1103/PhysRevLett.108.155501
they show reasonably convincing LEED (low energy electron diffraction) and STM (scanning tunneling microscope) images of the putative hexagonal close packed array of Si atoms.
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But will it blend?
FTFY
But will it form an oxide? (Score:3)
Good question. One of the great things about silicon from a device manufacturing perspective is that it forms an insulating oxide. Don't know if silicene will do that without compromising its desirable electronic properties. Maybe some of the modelers among us can tell what will happen to the electron structure when we start plugging oxygen atoms onto silicene?
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Silicene doesn't have to be used like bulk silicon-dioxide ingots. Silicene could be used on silicon wafers like bi-layer graphene stacks as a gate material, or maybe similar use to silicides as low-resitance local interconnect (although it doesn't seem like it would be better than say a salicide or self-aligning silicide).
Anyhow, it appears that silicene has a very strong resistance to oxidation.
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Note that the abstract linked to in the summary (http://prl.aps.org/abstract/PRL/v108/i15/e155501) speaks of "buckled" honeycomb. This is the surface of a Si crystal with diamond stucture. This is NOT the Si-equivalent of graphene, which has a flat or slightly wavy topology. I don't understand why everyone here is speaking of a graphene analogue, when it clearly is not!
It makes me wonder. . . (Score:2)
It makes me wonder if anything will ever replace silicon.
Re:It makes me wonder. . . (Score:4, Funny)
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