Graphene

Conversation heard between a visibly excited scientist S and a grumpy “ordinary” guy G in a busy café:

S - “...Do you have a pencil by your side? Good, now imagine this - take a “knife” and start “slicing” the graphite led. If you keep on doing it “long” enough you will soon get a one-atom thick sheet. Now, put it under a “powerful” microscope and you will see a chicken-wire structure of carbon atoms. This, my friend is graphene, the latest found allotrope of carbon. And if you had done this little 'experiment' earlier, you might have won the Nobel prize this year.”

G - “And what is so special about getting a sheet of atoms? And, a knife...”

S - “The knife part was just an imaginative tool, anyhow, the guys who invented it in 2004 used a scotch tape to peel off the graphene layer – so the example was not too far away! More importantly, doing so they disproved the age-old wisdom that a free standing monolayer is impossible to achieve in nature. Its a tremendous achievement in terms of physics...”

G - “Hah physics, a fat good that would do to me!”

S - “Not at all – and stop being so cynical! The best part of graphene is that charge-carriers in it are massless particles which move in near relativistic speeds.”

G - “And, you lost me over there.”

S - “OK, let me see. Compared to other materials, electrons in graphene travel much faster – at speeds of 10⁸ cm/s. Add to it, the fact, that even under ambient conditions, a graphene sheet is pure enough to ensure that electrons can travel a fair distance before colliding, and you have got a 'holy grail' for electronics engineers.”

G - “Hmm, interesting – but what's so fascinating about it?”

S - “Because it is the perfect recipe for making balistic nanodevices – electronic devices few nanometers long that would be able transmit charge at breath taking speeds for a fraction of power compared to present day CMOS transistors.”

G - “Ah! You mean too say that electronic devices made from graphene would be way faster and way less power hungry than those we have today. That makes it a perfect replacement for silicon based devices, doesn't it?”

S - “Well, its not that easy. You see silicon, or most of the materials used today in digital electronic devices are semi-conductors, i.e., there is a band-gap between conducting and non-conducting states. Graphene has no band-gap. Consequently, a transistor, which is the main building block of all digital devices we see nowadays, made from graphene, will have a very low ON-OFF ratio. I mean, though such devices will be fast, it will be very difficult to detect if it has a 1 or 0 stored in it.”

G - “Pooh, so much for the hoopla. It seems like another buzz word.”

S - “Not at all. First of all, graphene is easy to isolate and handle. Plus, it can still be used in analogue electronics; did you see that news about ultrafast transistor made from graphene. That still is something! These things may just revolutionise communication as we know it.  And this is just the tip of the iceberg. Due to their thinness they can be used as highly efficient sensors, e.g. for DNA. I have also heard that folks have developed graphene based ultra-capacitors, which might very soon be used to fuel everything, from your phone to your cars – you know green energy and all that. ”

G - “But still consumer electronics is where the action is. And if this material cannot be used to make digital stuff, then I am not buying it.”

S - “Wait! I haven't told you about bilayer graphene or graphene nano-ribbons, as yet. They do have band-gap and can be used to make ultra-fast transistors. As a plus, it is ambi-polar, which means you do not have to dope it, to switch between p and n- graphene – this alone makes it infinitely more flexible than other semiconductors. But wait, do you remember Tom Cruise doing his cool antics in-front of those transparent screens in 'Minority Report'? Graphene, in addition of being highly conductive is transparent too – which means sturdy, multi-functional. transparent touch-screens are not that far away.”

G - “Wow, now we are talking business.”

S - “If you have some time, you must listen to this lecture by K. Novoselov, one of the inventors of graphene, on possible applications. And I strongly recommend you to subscribe to http://graphenetimes.com/ to stay abreast of the latest developments in this field. ”

G -  “So why are we not seeing graphene in action as yet?”

S - “Simple - industrial scale production of graphene. Engineers have still not been able to come up with a way to produce pristine graphene of uniform quality at a large-scale. You cannot make an industry out of scotch-tape and pencil lead, you know! But for all means and purpose they are inching towards it. Plus, the physics of this material is not yet well-understood. Thus, it will be some time before it can be used efficiently at an industrial chain. But I tell you the future lies where processors will be made from multiple layers of graphene, with each layer acting as one 'core', and being way faster and way energy efficient than before.”

G - “You act foolishly enthusiastic!”

S - “Well I have reasons to be. After all life on our planet is carbon-based. Its high time that devices surrounding us in our daily life be carbon-based too!”

G - “Can't argue with that!”

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Contributed by Kaustuv Banerjee
Researcher (Graphene Technology)
Aalto University Finland
kaustuv.banerjee1[at]gmail.com