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Silicene Discovered: Single-layer Silicon That Could Beat Graphene To Market
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."
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.
I'm still waiting on the atom-thick holographic film, Holocene(tm).
You can hold down the "B" button for continuous firing.
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?
And the flexible version.... Pliocene
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
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.
I'm waiting for the censored version of the Oxygen-Boron layer: OBscene.
"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.
I don't care if it's 90,000 hectares. That lake was not my doing.
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.
"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.
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?
I thought saline replaced it -- wait -- what were you talking about again?
"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
Live today, because you never know what tomorrow brings
So late this decade or next decade at the latest Moore's law is dead.
Unless someone comes up with something clever again.
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.
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, 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.