Could Graphene Become the Next Silicon?

In summary: In its pure form, it is a highly conductive material due to its unique electronic structure. This makes it an ideal candidate for transparent electrodes in LCDs, as it would allow for better light transmission and more efficient use of electricity.The researchers also developed a method for producing large quantities of graphene, which has traditionally been a challenge. They used a technique called chemical vapour deposition to grow graphene on a copper substrate, which can then be transferred onto a flexible polymer film. This method allows for the production of large, high-quality graphene sheets, making it feasible for use in commercial applications.This latest advancement adds to the long list of potential applications for graphene, including faster and more efficient transistors
  • #36
Greater strength, stiffness, and temperature stability:

http://www.modplas.com/inc/mparticle.php?section=eweekly&thefilename=eweekly07012008_08"
 
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Physics news on Phys.org
  • #37
http://physicsworld.com/cws/article/news/35055;jsessionid=F5DFF82E9E07F69F166A729CBB0D0632"

Amazing! The world's strongest material! And as a bulk material it should be stronger than nanotubes, since you can use both sides of planar graphene sheets for the Van Der Waals cohesion, as opposed to nanotubes which only let you use their outer surface.

I wonder if you could make super-blimps with this thing, or maybe gigantic air-pressurized domes on Mars? With graphene, the sky's the limit!
 
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  • #38
More on graphene's strength:

http://www.technologyreview.com/Nanotech/21098/?a=f
 
  • #41
http://www.nanowerk.com/news/newsid=6499.php"

This achievement may pave the way for the application of graphene to VLSI.
 
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  • #42
"Carbon nanotubes, but without the 'nano'"

http://physicsworld.com/cws/article/news/35364;jsessionid=E6628E7F95243A663D2F2E964421CABF


Regards, Hans
 
  • #44
"IQE to develop graphene-based RF integrated circuits for US fed program"

http://www.solid-state.com/display_news/167603/5/HOME/IQE_to_develop_graphene-based_RF_for_US_fed_program


Regards, Hans
 
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  • #45
As this debate is going on, I think I need to add this...
"Future Nanoelectronics May Face Obstacles"
Umea University (Sweden) (09/08/08)
http://www.info.umu.se/NYHETER/PressmeddelandeEng.aspx?id=3219

If findings are correct, graphene will not become the next silicon, regardless of its greatness. It does have an astounding number of incredible properties, and can be used elsewhere, tho.
 
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  • #46
http://nanotechweb.org/cws/article/tech/35723

Technology update

Sep 8, 2008
STM cuts graphene to size

Researchers in Hungary and Belgium have developed the most precise nanolithography technique ever. Levente Tapasztó of the Research Institute for Technical Physics and Materials Science in Budapest and colleagues have already used the method, which employs the tip of a scanning tunnelling microscope, to pattern tiny nanostructures (ribbons) into a graphene sheet. The technique makes it possible to build entire working circuits and avoids the disadvantages of "bottom up" methods that rely on assembling individual building blocks, such as carbon nanotubes.

"We have realized truly nanometre precision lithography," Tapasztó told nanotechweb.org. "This allows us to fabricate nanostructures with the desired atomic structure and therefore good electronic properties."

The technique allows materials to be "cut" to the required shape and dimensions at the nanoscale. This is a huge step forward, says Tapasztó, because until now researchers had to rely on finding suitable blocks, like carbon nanotubes with the correct structure, to fabricate nanoscale electronic devices.

The team, which includes researchers from Facultés universitaire Notre Dame de la Paix in Namur, Belgium, made nanostructures by bombarding a graphene sheet with electrons emitted from an atomically sharp tip positioned just a few angstroms above the surface of the material. This "local access" ensures that the technique is precise. By moving the tip along a given geometry, different shapes can be patterned. A big advantage of the technique is that it allows in-situ atomic-scale resolution imaging of the sample immediately after it has been shaped.

By controlling both the width and crystallographic orientation of the nanoribbons, the method is the first to be able to fully engineer the electronic band gap of graphene. "Moreover, the accuracy of STM lithography also allows for downscaling, which is important since it enables us to open energy gaps large enough for room-temperature operation of graphene-based electronic devices," explained Tapasztó. Indeed, the team has managed to reduce a nanoribbon to just 2.5 nm wide (about 20 carbon atoms). This is far beyond the capabilities of current state-of-the-art electron beam lithography, which can only go down to around 20 nm.

Finally, "edge disorder" of ribbons is a big problem in these nanostructures because it affects their electronic properties, resulting in poor reproducibility. The new STM method produces smooth edges and so overcomes this challenge too.

"In principle, our method provides all of the solutions needed to fabricate functional nanoelectronic circuits from graphene," said Tapasztó. "It can be considered as the 'next step' in nanoscale electronic device fabrication since not only individual nanostructures but more complex nanoarchitectures can be made".

The proof-of-principle method now needs to be scaled up so that it can be used in industrial processes – a goal that is very challenging but not unrealistic, says the team.

The researchers now plan to make more complex structures from graphene and perform transport measurements to demonstrate that the circuits operate. And, although the method was originally developed for patterning graphene, it could be adapted and optimized for other materials, adds Tapasztó.

The work was reported in Nature Nanotechnology.
 
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  • #47
Hydrazine yields larger graphene sheets, hundreds of square-microns in size:

http://www.technologyreview.com/computing/21683/?a=f
 
  • #49
Graphene memory also announced:

http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=9123838

O Beloved Graphene, is there anything you cannot do?
 
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  • #51
Graphane

Oh look, it's Son of Graphene:

http://www.technologyreview.com/computing/22038/
 
  • #52
Graphene Goes Green:

http://www.technologyreview.com/business/22062/?a=f

Ultimate Ultra-capacitors!
 
  • #53
You have to realize that these "amazing" properties of graphene are observed in single crystals that are exfoliated from scotch tape or produced at very high temperatures from SiC crystals. Nobody has been able to synthesize multilayer, single crystal graphene in a way that would be compatible with existing CMOS processes. Even single crystal graphene has unimpressive electron/hole mobility without post-heating to remove impurities. Also, there is no reliable way of introducing a bandgap, so practical graphene transistors are a pipe dream.

It would be nice if someone could develop a CVD or ALD technique for growing graphene sheets at lower temperatures. The only problem is that these sheets would be riddled with defects. The only real application I can see for graphene is as a material for global interconnects, where its superior electromigration resistance could be put to use.
 
  • #54
Electromigration itself has been shown as a useful way to get rid of defects in graphene and nanotubes.

I say the more investigation the better, as sooner or later someone will come up with a breakthrough method to make graphene part of the next killer app.

But certainly, if you know of a better candidate to provide the next leap forward in capabilities, I'd be glad to hear of it.
 
  • #55
Read this:

http://compoundsemiconductor.net/cws/article/lab/37745

News

Feb 11, 2009
Argon atmosphere enhances graphene-on-SiC

Innovative carbon monolayer production method avoids high-vacuum annealing and opens the subject up to a wider range of researchers.

German and US researchers have driven forward methods for producing graphene by annealing SiC substrates, producing the largest homogeneous epitaxial domains of the carbon material yet described.

The team, led by scientists from the University of Erlangen-Nuremberg, found that heating SiC in argon produces significantly better quality graphene than methods using ultra-high vacuum conditions.

Analyses of the resulting samples at Erlangen and at the Fritz-Haber-Institute, Berlin, and Lawrence Berkeley National Laboratories, California, showed graphene terraces up to 3 µm wide and 50 µm long. This compares with 30 to 200 nm for the vacuum approach.

The group's progress towards effectively producing the material comprised of a single monolayer of graphite was published online in Nature Materials on February 8. “We can unambiguously conclude that the large atomically flat macro-terraces are homogeneously covered with a graphene monolayer,” wrote author Thomas Seyller in the paper.

“We were looking for practical ways to avoid the ultra-high vacuum environment for graphene growth, which is almost impossible to scale up to mass production,” Seyller told compoundsemiconductor.net. Using a type of vertical cold wall reactor that has previously performed post-growth annealing, it seems that the goal has been attained.

“It appears much simpler than the growth under ultra-high vacuum,” commented Pierre Mallet, a leading graphene researcher at Institut Néel in France. “I believe many labs and companies will try to synthesize their own epitaxial graphene-on-SiC using this method.”

Hot topic

Graphene is formed as silicon evaporates from the SiC substrate, and the 900 mbar argon atmosphere the researchers use reduces the rate at which this occurs. The argon deflects silicon atoms back towards the substrate, meaning that silicon desorption doesn't begin until 1500°C, compared to 1150°C for the vacuum method.

Erlangen's annealing method therefore occurs at 1680°C, enhancing diffusion of silicon and carbon atoms and improving surface morphology compared to the 1280°C vacuum method.

A homogeneous layer is important because a single monolayer of graphene is a gapless semiconductor, but additional carbon monolayers change the film's electronic structure.

Previously, large epitaxial graphene films have been formed on the transition metal ruthenium, but for this to be useful electronically the fragile graphene layer must be transferred to an insulating substrate. By using the insulating, on-axis, Si-terminated, Si(0001) wafers produced by substrate vendor SiCrystal, Seyller and his colleagues had a clear advantage.

Electron mobility measurements showed a highest value of 2000 cm2V-1s-1 for graphene grown in argon, compared to 710 cm2V-1s-1 for vacuum-grown material. This is well short of the 200,000 cm2V-1s-1 reported by the discoverers of graphene at the University of Manchester.

“Compared to exfoliated graphene, the mobility of our epitaxial graphene films is still much below expectations,” Seyller conceded. “We need to understand the reasons for this and develop strategies for improvement.”

Mallet suggests that the price of SiC substrates and the vertical cold-wall reactor used could also be offputting to some, but he is generally enthusiastic about the method.

“The impact will be very high,” Mallet said. “Not only the graphene-on-SiC community should be interested, but the entire condensed matter community.”
 
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  • #57
Graphene Nano-ribbons Made Easily from Nanotubes:

http://www.technologyreview.com/computing/22503/?a=f

Amazing, now semi-conducting graphene nano-ribbons can be made in bulk, simply by cleaving open carbon nanotubes lengthwise.
 
  • #58
"Graphene Shows High Current Capacity and Thermal Conductivity"

http://www.physorg.com/news168103210.html
(PhysOrg.com) said:
-- Recent research into the properties of graphene nanoribbons provides two new reasons for using the material as interconnects in future computer chips. In widths as narrow as 16 nanometers, graphene has a current carrying capacity approximately a thousand times greater than copper—while providing improved thermal conductivity.
Regards, Hans
 
  • #59
"From graphene to graphane, now the possibilities are endless"

http://www.physorg.com/news168251755.html
(PhysOrg.com) said:
One advantage of graphane is that it could actually become easier to make the tiny strips of graphene needed for electronic circuits. Such structures are currently made rather crudely by taking a sheet of the material and effectively burning away everything except the bit you need. But now such strips could be made by simply coating the whole of a graphene sheet - except for the strip itself - with hydrogen. The narrow bit left free of hydrogen is your conducting graphene strip, surrounded by a much bigger graphane area that electrons cannot go down.
Regards, Hans
 
  • #60
"New form of carbon created" (Multilayer Epitaxial Graphene)

http://physicsworld.com/cws/article/news/40048
physicsworld.com said:
The new material is made from layers of graphene -- sheets of carbon atoms just one atom thick -- stacked on top of one another in such a way that each layer is electronically independent. The researchers claim that the material, dubbed multilayer epitaxial graphene (MEG), could be used in carbon electronics instead of costly single and double layer graphene sheets.


Regards, Hans
 
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  • #61
This sounds great, Hans - but as always, what is the quality like?

Here's another story about commercial production of graphene for conductive inks:

http://www.technologyreview.com/business/23129/
 
  • #62
sanman, while I can't be too specific, the quality is very impressive as far as graphene goes from what I have seen - apparently much less corrugated and discontinuous than graphene made using the scotch tape method. To call it a "new form of carbon" is probably spin put on it by the journalist, as that particular group has been working on that material for a couple years now. It is extremely curious how they managed to create a material that decouples the layers into individual sheets though; some of the more recent literature shows all sorts of weird effects as a result of the misalignment in the layers.

Interesting link though: I have always thought myself that graphene is currently best suited for composite materials. Making all-graphene things is so much harder.
 
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  • #63
I think they're claiming that the specific difference in the chiral angle/orientation between the sheets is what causes the decoupling. How they've achieved that specific difference though, is what's interesting.

Let's see how quickly they can make transistors out of it.
 
  • #64
As it turns out when I was looking at the arXiv paper linked in that phyiscsworld article, it appears that this very recent paper http://arxiv.org/ftp/arxiv/papers/0908/0908.0017.pdf has an author in common. In it they talk about transistors made out of multilayer epitaxial graphene, which is (apparently) the term they use to describe graphene grown on the "C-face" silicon carbide. The on/off ratios are quite modest, which they blame on some substrate problems, so as always there's a catch :smile:
 
  • #65
http://graphenetimes.com/2009/07/epi-sic-first-direct-observation-of-a-nearly-ideal-graphene-band-structure/

EPI SiC ** First direct observation of a nearly ideal graphene band structure

Authors: M. Sprinkle, D. Siegel, Y. Hu, J. Hicks, P. Soukiassian, A. Tejeda, A. Taleb-Ibrahimi, P. Le Fèvre, F. Bertran, C. Berger, W.A. de Heer, A. Lanzara, E.H. Conrad

Angle-resolved photoemission and X-ray diffraction experiments show that multilayer epitaxial graphene grown on the SiC(000-1) surface is a new form of carbon that is composed of effectively isolated graphene sheets. The unique rotational stacking of these films cause adjacent graphene layers to electronically decouple leading to a set of nearly independent linearly dispersing bands (Dirac cones) at the graphene K-point. Each cone corresponds to an individual macro-scale graphene sheet in a multilayer stack where AB-stacked sheets can be considered as low density faults.
 
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  • #66
FirstYearGrad said:
As it turns out when I was looking at the arXiv paper linked in that phyiscsworld article, it appears that this very recent paper http://arxiv.org/ftp/arxiv/papers/0908/0908.0017.pdf has an author in common. In it they talk about transistors made out of multilayer epitaxial graphene, which is (apparently) the term they use to describe graphene grown on the "C-face" silicon carbide. The on/off ratios are quite modest, which they blame on some substrate problems, so as always there's a catch :smile:

The defining trait of a transistor (or a SWITCH for that matter) is the ON/OFF ratio, i.e, non-linearity in circuit characteristics.

In the upper level of hierarchy, the circuit designer does not care at all whether you make your SWITCH out of carbon, silicon, or spin, etc...

Graphene is a zero band-gap semiconductor, it's almost as if it's a short circuit... So currently, there's NO WAY you can fabricate a functional transistor out of graphene UNLESS you find a very good way to induce a band-gap to improve the ON/OFF ratio.

I don't find it surprising that ON/OFF ratios are "quite modest" since this is the single most important problem of graphene. I can't imagine the substrate being the culprit here, because it's a fundamental problem related to the bandstructure of graphene.

It's not another catch, it is THE catch with graphene.
 
  • #68
It still is the mainstream problem... And it will likely be the deal-breaker for graphene.

Of course, striping it and cutting it fine can create a further constriction (ultimately rendering the sheet as 1D rather than 2D) but this is just a fractal solution... Graphene Nanoribbons are likely to be larger in width than tens of nanometers, because you need some decent conductance to utilize it as an electrical switch.

I hear from experimentalists that it could potentially be a valuable interconnect though... Just not a replacement for CMOS...
 
  • #69
Well, interconnects are considered a key bottleneck for increased multiparallelism, in GPUs/vector-processors, for example. So more efficient interconnects from graphene could help address that. As you know, right now GPGPUs (General Purpose Graphics Processing Units) are trying to battle with CPGPUs (Central Processing / Graphics Processing Units) over which becomes the processor of choice for the future. The former are almost purely vector processors with some additional logic to accommodate conventional CPU tasks, while the latter are traditional Central Processing cores with Graphics Processing cores integrated onto the same die. The GPGPU is optimized for throughput by using many parallel cores, while the CPGPU is optimized to reduce latency. Maybe graphene could tip the scales in favor of the GPGPU to become the dominant platform.
 
  • #70
"Camera flash turns an insulating material into a conductor"

http://www.printedelectronicsworld....ial_into_a_conductor_00001684.asp?sessionid=1

Printed Electronics said:
Using patterns printed on a simple overhead transparency film as a photo-mask, flash reduction creates patterned graphene films. This process creates electronically conducting patterns on the insulating graphite oxide film essentially a flexible circuit.


Regards, Hans
 

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