graphene ‘it’s role in electronic world.’

8/4/2019 Graphene Its role in electronic world.

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Graphene :Its role in electronicworld.

Past


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BRIEF HISTORY

Discovered at The University of Manchester back in 2004,by Professor Andre Geim FRS and Royal Society Researchcolleague Dr Kostya Novoselov.

One atom thick

Optically transparent Chemically inert Excellent conductor


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The Processor

A central processing unit (CPU ), or sometimes simply processor, is the component in a digital computer that interprets computerprogram instructions and processes data. CPUs provide thefundamental digital computer trait of programmability, and are one ofthe necessary components found in computers of any era, alongwith primary storage and input/output facilities. Beginning in the mid-1970s, microprocessors of ever-increasing complexity and power

gradually supplanted other designs, and today the term "CPU" isusually applied to some type of microprocessor.


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The 65nm Processor

The technology of today Benefits of the 90-65nm cross-over Increase in multimedia performance (video, audio, data

streaming)

Two new layers of hardware based security (protection againsthackers and viruses) Advanced manageability for IT (remote problem resolution) Acceleration technology that improves the speed for network

traffic (faster download and communication)


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The 65nm Processor

The 65nm technology 35nm gate length 1.2nm gate oxide NiSi for low resistance

2nd generation strained Siliconfor enhanced performance These features prevent transistor leakage and reducepower consumption


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The 45nm Processor

Benefits of the 65-45nm cross-over Twice improvement in transistor density Five times reduction in source-drain leakage power 20% improvement in transistor switching speed 30% reduction in transistor switching power Ten times reduction in transistor gate oxide leakage for lower

power requirements and increased battery life More performance for exponentially less cost


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The Future

Intel plans to use extreme ultra-violet lithography to printelements as small as 32 nm and beyond (expectations 2009)

AMD and IBM will cooperate to devise techniques formanufacturing chips using the 32-nanometer and 22-nanometerprocesses (expectations 2009 and 2011)

Other options include replacing the use of Silicon by othermaterials such as Germanium Another development relates to the use of Graphene


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Why replacing silicon?

For the past four decades the silicon industry has delivered a continuouslyimproving performance at ever-reduced cost

Those breakthroughs were achieved by physical scaling of the silicon but infew years it approaching an end,in part because silicon is reaching its physicallimit.

The remarkable increase in computer speed over the last Physical limitations such as off-state leakage current and power density pose

a potential threat to the performance enhancement that can obtained bygeometrical scaling


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AT the heart of the problem is the poor stability ofsilicon.

If silicon shaped in elements smaller than 10nanometers in size at this spatial scale allsemiconductors including silicon oxidise decomposeand uncontrol migrate along surface like water dropletson a hot plate.


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The Use of Germanium

Why using Germanium? As seen in class mobility is one of the most important characteristics for

electronic applications According to the International Technology Roadmap for Semiconductors,

even with strain engineering, metal gates and high-k dielectrics,

semiconductors with higher mobility will be needed to continue scaling beyondthe 22nm technology node III/IV compounds such as InSb, InAs or InGaAs have high electron mobility but

same hole mobility as Si which is an issue for p-MOS devices Germanium is one solution


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The Use of Germanium

Properties Si Ge GaAs

Atoms/cm3 5.02 x 1022 4.42 x 1022 4.42 x 1022

Effective mass electrons (m/m0) 0.26 0.082 0.067

Effective mass holes (m/m0) 0.69 0.28 0.57

Electron affinity (V) 4.05 4.0 4.07

Energy gap (eV) 1.12 0.67 1.42

Mobility electrons (cm2/V s) 1500 3900 8500

Mobility holes (cm2/V s) 450 1900 450


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Problems with the use of Ge

Germanium use will allow research and development to reach the 22nm nodehowever: The low bandgap (0.67eV) and low melting point (937C) poses challenges for

device design and process integration Ge wafers offer poor mechanical strength and are much more expensive than

Si wafers For n-MOS devices the presence of specific surface defects directly degrade

the channel mobility and limit the current drive


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The use of carbon nano tube infuture


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The Use of carbon nanotubes

Carbon nanotubes Carbon nanotubes is the recentally allotropes of the

carbon. Metallic nanotubes display quantized ballistic conduction at room

temperature conductance can be controlled by applying an electrostatic gate Have already been used to make simple transistors and logic

gates


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Nanotubes

Nanotubes many limitations - limited consistency in size and electric properties - Difficulty integrating nanotubes into electronics efficiently- High electrical resistance at junctions between nanotubes and thewires connecting them. -there is no method currently avaliable to accurately place hundered of millionsnanotubes where they would be needed in oreder to form integrated circuit -A lack of cirality control during production leads to a mixture of mettalic andsemicounducting nanotube. The solution Using Graphene layers or ribbons - Exact same properties as Carbon nanotubes with out

the limitations.


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Preparation of graphene

The materials were created by extrating individualatomic plane from conventional bulk crystal by using atechnique called micromechanical cleavage.

Depending on the parent crystal their one-atom thick

counterparts can be metals semiconductors insulatorsmagnets etc.

Using carbon as the parent crystal in micromechnaicalcleavage graphene is created.


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Graphene layers

Advantages o The graphene layers are only 10 atoms thick

(Miniaturization) o High efficiencies and low power consumption o Devices made from graphene layers can be made using

standard micro-electric processing techniques(Mass production of graphene devices)

Such standard lithographic methods


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The Progress of GrapheneTransistors

Many universities have created transistors from graphene,approximately 80nm The goal is to make these transistors 10nm where the devices will display ballistic transport .


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IBM scientist have fabricated nano-scale graphene fieldeffect transistors and demonstrated the operation ofgraphene transistors at the GHZ frequency range.

They achieved a cut-off frequency of 26 GHZ for

graphene with a gate length of 150 nm. The highestfrequency obtained for graphene so far. By imporving the gate dielectric materials,the

perfomance of these transistors could be furtherenchanced.

They expect that THZ graphene transistors could brachieved in an optimized graphene transistor with agate length of 50 nanometer .


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Transistors made by the use ofgraphene


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Eletrons move through graphene with almost noresistance ,generating little heat .

What more graphene is itself a good thermal conductorallowing heat to dissipate quickly.

Silicon transistors stuck in the gigahertz range but withgraphene do a terahertz a factor of a thousand over agigahertz.


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GRAPHENE TRASISTORproperteis

Graphene can transport electrons extremily quicklywhich could allow very fast switching speeds inelectronics.

Graphene based transistors for example could run at

speeds a hundered to a thousand times faster thantoday. Unlike all other materials, graphene remains highly

stable and conductive even when it is cut into devicesone nanometer wide.


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Graphene transistors start showing advantage andgood performance at sizes below 10 nanometers theminiaturization limit at which the silcon technology ispredicted to fail.

Being extremely thin and a semiconductors electronsmove through graphene at extremely high speed .this isbecause they behave like relativistic particles that haveno rest mass.


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3D VIEW


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Problems with graphene

Graphene hasnt always looked like a promisingeletronic material for one thing it doent naturally exhibitthe type of switching behaviour required for computing .

Silicon which can be switched off,graphene continuws

to conduct a lot of electrons even in its off state. This isthe main draw back


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Early Graphene resistors leaked current o Working on single electron transistor using quantum dots to

solve this problem. Quantum dots at room temperature are not stable

enough.

No fabrication techniques available to produce the 3nmquantum dots needed for the single electron transistor.

This requires the manufacturer to once again rely onluck to produce the right sized quantum dot. This bringsus back to square one as it is a similar problem withnanotubes


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Future computer


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Sources

http://www.nature.com http://physicsweb.org/articles/news/8/6/18 http://gtresearchnews.gatech.edu/newsrelease/graphene.htm http://www.technologyreview.com/Infotech/18264/page1/ http://www.physics.gatech.edu/npeg/npeg.html http://en.wikipedia.org/wiki/Moore's_law http://www.eetimes.com/news/semi/showArticle.jhtml?articleID=196901271 http://www.amd.com/us-

en/Processors/ProductInformation/0,,30_118_9485_13041%5E14633,00.html

http://www.intel.com/technology/silicon/65nm-cross-over.htm Ibm computer


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THANK YOU

graphene ‘it’s role in electronic world.’

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