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Silicene Discovered: Single-layer Silicon That Could Beat Graphene To Market

Soulskill posted more than 2 years ago | from the a-few-months-before-never dept.

Hardware 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."

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And now? (0)

Anonymous Coward | more than 2 years ago | (#39848165)

May I guess the next few years of discoveries? Lithicene, Sodicene, Potassicene... well, I need hardly go on...

Re:And now? (5, Insightful)

tocsy (2489832) | more than 2 years ago | (#39848273)

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.

Re:And now? (0)

Anonymous Coward | more than 2 years ago | (#39848477)

I think you are confused - graphene certainly does NOT have sp3 hybridize C atoms as in diamond. Graphene (as the name implies) is derived from the hexagonal graphite layers (sp2 hybridized) C.

So graphene and silicene are actually very different!

Re:And now? (1)

Anonymous Coward | more than 2 years ago | (#39848661)

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 geometry, so I will not completely dismiss the idea of careful lead sculptures being a favored circuitry.

Re:And now? (1, Insightful)

Anonymous Coward | more than 2 years ago | (#39849603)

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.

Re:And now? (2)

noobermin (1950642) | about 2 years ago | (#39852571)

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? (0)

Anonymous Coward | about 2 years ago | (#39854827)

Wrong! Si double bonds are *very* unstable. So Si is unable to have the "special" bonding in graphene. Learn some chemistry, kids!

Re:And now? (4, Informative)

tocsy (2489832) | more than 2 years ago | (#39848955)

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.

Re:And now? (0)

Anonymous Coward | more than 2 years ago | (#39849517)

You're correct, graphene (and apparently now silicene) has sp2 hybridization

Actually this picture
http://www.extremetech.com/wp-content/uploads/2012/04/Silicene_Cluster.jpg
looks very much like sp3-diamond like hybridization. I'd be very surprised if Si in the form of graphene was stable. It's probaly react immediately with oxygen to a SiO2 or substoichiometric SiO(2-x) monolayer.

Re:And now? (1)

Annirak (181684) | more than 2 years ago | (#39850015)

It'll likely be manufactured under heavy vacuum, then sealed, and never exposed to any O2.

Re:And now? (1)

ChrisMaple (607946) | about 2 years ago | (#39859673)

Note, however, that the insulator commonly used in silicon systems is silicon dioxide, formed by the in place oxidation of silicon. Forming an enduring insulator on a silicene layer is going to be tricky. Come to think of it, I bet forming an insulator on a graphene layer is also difficult.

Re:And now? (0)

Anonymous Coward | about 2 years ago | (#39855327)

this finding could replace silicon or combined silicon
silicon or combinedsilicon or combined [webdangtin.com]

Re:And now? (1)

hamburger lady (218108) | about 2 years ago | (#39856605)

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.

Re:And now? (1)

Anonymous Coward | more than 2 years ago | (#39848279)

Plasticene?

You forgot! (0)

Anonymous Coward | more than 2 years ago | (#39848281)

May I guess the next few years of discoveries? Lithicene, Sodicene, Potassicene... well, I need hardly go on...

And of course, Graphenicene!

Re:And now? (5, Funny)

game kid (805301) | more than 2 years ago | (#39848287)

I'm still waiting on the atom-thick holographic film, Holocene(tm).

Re:And now? (4, Funny)

sconeu (64226) | more than 2 years ago | (#39848397)

And the flexible version.... Pliocene

Re:And now? (5, Funny)

fredrated (639554) | more than 2 years ago | (#39848677)

I'm waiting for the censored version of the Oxygen-Boron layer: OBscene.

Re:And now? (1)

Anonymous Coward | more than 2 years ago | (#39850553)

Toil onwards, nerds. I'll be hangin down at Starbucks with me iPhone, iPad, and Macbook Air as part of the self-referential Hipsterscene

Re:And now? (1)

Khyber (864651) | more than 2 years ago | (#39851977)

He wins, that's about as mono-layer as you can get!

Re:And now? (1)

kj_kabaje (1241696) | about 2 years ago | (#39853963)

I thought mono was part of the MS ecosystem?

Re:And now? (1)

Khyber (864651) | about 2 years ago | (#39854103)

Mononucleiosis, maybe!

Re:And now? (0)

Anonymous Coward | more than 2 years ago | (#39852065)

Oh god. you must be one of those Y2K+ kids. Get off my 90s internets! The geeks (original) will rule again!

Re:And now? (1)

gstrickler (920733) | more than 2 years ago | (#39850221)

But no one has asked the really important question. How do you pronounce silicene?

Re:And now? (1)

RaceProUK (1137575) | about 2 years ago | (#39855547)

I'd guess 'silly seen'

Re:And now? (1)

moteyalpha (1228680) | more than 2 years ago | (#39848311)

Valence 4. I would assume Germainiumicene will be the next with a band gap of .67

Re:And now? (1)

Anonymous Coward | more than 2 years ago | (#39848375)

Thought this might help your predictions [ptable.com] Notice where Carbon and Silicone are.

Re:And now? (0)

Anonymous Coward | more than 2 years ago | (#39849765)

I'm ready for Apple to steal my trademark on iRoncene.

Beat Graphene to Market? (5, Interesting)

sirdude (578412) | more than 2 years ago | (#39848333)

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? (5, Funny)

InvisibleClergy (1430277) | more than 2 years ago | (#39848429)

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".

Re:Beat Graphene to Market? (2, Informative)

Anonymous Coward | more than 2 years ago | (#39849073)

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.

Re:Beat Graphene to Market? (1)

NatasRevol (731260) | more than 2 years ago | (#39849193)

Nope.

Re:Beat Graphene to Market? (0)

Anonymous Coward | more than 2 years ago | (#39849191)

Silicene! You lack of faith graphenses me.

Re:Beat Graphene to Market? (1, Insightful)

Sarten-X (1102295) | more than 2 years ago | (#39848837)

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?

Re:Beat Graphene to Market? (2)

mosb1000 (710161) | more than 2 years ago | (#39849501)

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.

Re:Beat Graphene to Market? (1)

Anonymous Coward | more than 2 years ago | (#39850275)

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.

Re:Beat Graphene to Market? (2)

Neil Boekend (1854906) | about 2 years ago | (#39854781)

The basic technique used in cookie graphene [slashdot.org] is quite cheap, and if you choose to produce it directly on the final substrate the handling should be easy. Dunno what the exact recepie of silicene would be, but sand in a vacuum oven would be my first try.
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.

Re:Beat Graphene to Market? (0)

Anonymous Coward | about 2 years ago | (#39855445)

Diamond, which is the counterpart of crystalline Silicon has a huge bandgap. Graphen has no bandgap at the K-point (six dirac-cones) which is due to the two-dimensionality and the hexagonal arrangement and the sp2 hybridization. The same applies to silicene. Silicene has no bandgap at the K-point; it features the same dirac-cone properties as graphene, simply due to symmetry reasons.

Re:Beat Graphene to Market? (1)

DCFusor (1763438) | about 2 years ago | (#39852823)

Maybe, maybe not. Tech exists for photolith, doping and etching and growing oxide, and generally doing you-name-it to silicon that has no counterpart for graphene whatever. It's a pretty big deal, actually. No one's made a graphene integrated circuit AT ALL. Silicon, on the other hand...

Re:Beat Graphene to Market? (1)

jsfs (1329511) | about 2 years ago | (#39853959)

Well, if it's similar to graphene in ease of making and useful properties, then yes, it could beat graphene to market in actual consumer-type devices because it's easier to integrate into current manufacturing based around silicon. Yes, the headline is optimistic and smells a bit of propaganda, but anything similar to current stuff is more likely to get adopted quickly.

Physical Limits (1)

mhajicek (1582795) | more than 2 years ago | (#39848349)

"silicon — a material which will probably reach its physical limits in the next 5-10 years" Haven't they been saying that since 1980?

Re:Physical Limits (4, Funny)

Jeremi (14640) | more than 2 years ago | (#39848849)

"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 (0)

Anonymous Coward | more than 2 years ago | (#39849491)

or Moore's Law will at least continue until the end of the world. It is 2012 after all.

Re:Physical Limits (5, Interesting)

Kjella (173770) | more than 2 years ago | (#39850603)

"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

...and smaller than this just isn't possible. With Intel's tick-tocks there's two years between ticks so 14 years at that rate. But long before that you can start counting the lattices on your fingers, already at 5nm there's only nine left (9*0.55 = ~5) and that's only 6 years away. So late this decade or next decade at the latest Moore's law is dead.

Re:Physical Limits (4, Insightful)

mhajicek (1582795) | more than 2 years ago | (#39851091)

So late this decade or next decade at the latest Moore's law is dead.

Unless someone comes up with something clever again.

Re:Physical Limits (1)

Kjella (173770) | about 2 years ago | (#39853603)

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.

Re:Physical Limits (1)

mhajicek (1582795) | about 2 years ago | (#39856787)

Perhaps someone will find a way to make a single atom perform the function of multiple transistors.

Re:Physical Limits (1)

benthurston27 (1220268) | more than 2 years ago | (#39865965)

Obviously you just start engraving the circuitry on the surface of the atom.

Re:Physical Limits (2)

YoopDaDum (1998474) | about 2 years ago | (#39855011)

Yes. And let's not forget that Moore's law is not related to the maximum transistor density achievable at a given time, but to the transistor density achievable at the lowest cost (see Moore's original paper [intel.com] , the emphasis on cost is very clear).

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, and people go to 28nm for performance (lower power / higher frequency or ability to integrate bigger functions), not (yet) for cost reduction. In time 28nm will become cheaper than 40nm, but strictly speaking in term of Moore's law, the reference today should still be 40nm (I'm taking TSMC as a reference BTW, YMMV with other fabs).

I expect that as we shrink further, the gap between the date a smaller process is introduced and the date it becomes cheaper than the previous node will increase, and maybe at some point cost will just increase. That will be the end of Moore's law.

There's a lot of interest riding on the continuation of Moore's law, particularly from companies that gain a competitive advantage from being among the first to get access to a smaller node. This means Intel of course, but even a lot of big fabless companies have better access to a smaller node compared to smaller fabless ones for example. The day Moore's law, then shrinking, stops, we can expect laggards in process to catch up eventually and this advantage would disappear. That would be quite a change. So let's not expect candid assessments on Moore's law status, there's just too much money involved. But among the less impacted players there's some noise starting to be heard. I noted recently the ARM CTO saying we should expect big changes, and sooner then most people expect. I wouldn't be surprised if it was related to this.

Put them together and you have.. (-1)

Anonymous Coward | more than 2 years ago | (#39848391)

You got your Silicine in my Graphine!!

You got your graphine in my Silicine!!

A Si mono-layer will grow a natural oxide fast (5, Interesting)

Sigurd_Fafnersbane (674740) | more than 2 years ago | (#39848399)

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.

Bandgap? (0)

Anonymous Coward | more than 2 years ago | (#39848655)

I thought they already figured out a way to induce a bandgap in graphene. Was I mistaken?

Abstract from one of the reports (3, Informative)

ridgecritter (934252) | more than 2 years ago | (#39848975)

"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.

Re:Abstract from one of the reports (0)

Anonymous Coward | more than 2 years ago | (#39849173)

But will it form an oxide?

Re:Abstract from one of the reports (1)

ZeroSumHappiness (1710320) | more than 2 years ago | (#39849361)

But will it blend?

FTFY

Re:Abstract from one of the reports (0)

Anonymous Coward | more than 2 years ago | (#39849931)

That would be Blendocene.

But will it form an oxide? (2)

ridgecritter (934252) | more than 2 years ago | (#39849581)

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?

Re:But will it form an oxide? (1)

slew (2918) | about 2 years ago | (#39852587)

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.

Re:Abstract from one of the reports (0)

Anonymous Coward | more than 2 years ago | (#39849731)

in a house?
with a mouse?

Re:Abstract from one of the reports (0)

Anonymous Coward | more than 2 years ago | (#39850133)

"compatibility with Si-based electronics": What does it mean? Silicen was grown on (111) silver. Where is the mentioned compatibility?
Next: either you want a dirac like dispersion relation, then there is no band gap, or you want a band gap as in Si-bulk, then there is no dirac like fermion.

Re:Abstract from one of the reports (2, Informative)

Anonymous Coward | more than 2 years ago | (#39850329)

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!

Re:Abstract from one of the reports (0)

Anonymous Coward | more than 2 years ago | (#39850395)

Thanks for pointing out that. It means no clean sp2-hybridization and no clean Dirac cone.

Still Waiting (0)

Anonymous Coward | more than 2 years ago | (#39849243)

It's only 5-10 years away like my permanent hair replacement procedure was 5-10 years ago. I'm still bald.

It makes me wonder. . . (1)

mosb1000 (710161) | more than 2 years ago | (#39849355)

It makes me wonder if anything will ever replace silicon.

Re:It makes me wonder. . . (4, Funny)

neo-mkrey (948389) | more than 2 years ago | (#39849761)

I thought saline replaced it -- wait -- what were you talking about again?

s/electrical/mechanical/ (1)

OneAhead (1495535) | more than 2 years ago | (#39851925)

You will have heard a lot about graphene, especially with regard to its truly wondrous electrical properties

In most press releases about graphene I read lately, the focus was on its mechanical properties, and the fact that it is conductive would be merely an (often convenient) side effect.

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