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Graphene

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Graphene A modern material with unique physical and electrical properties that could reshape our future. By: Steven Douglas 4/24/15 Outline: Introduction to graphene. – PowerPoint PPT presentation

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Title: Graphene


1
Graphene
  • A modern material with unique physical and
    electrical properties that could reshape our
    future.
  • By Steven Douglas
  • 4/24/15

2
Outline
  • Introduction to graphene.
  • History.
  • Physical properties.
  • Electrical properties.
  • Other properties.
  • How graphene is created.
  • Graphenes current uses.
  • Batteries
  • Capacitors
  • Transistors
  • Graphenes future.
  • Challenges surrounding graphene.
  • Summary/Conclusion
  • Key concepts.
  • References.

3
Introduction to Graphene
  • The first 2-dimensional material ever discovered.
  • One-atom thick of carbon atoms arranged in a
    hexagonal lattice.
  • Found in graphite, coal, and created in other
    fashions.
  • Hard to manufacture in large quantities, just
    about all graphene produced is used for RD
    within companies and universities.
  • The strongest, lightest, and most conductive
    material known to man.

4
Graphenes short history
  • Discovered by Andre Geim and Konstantin Novoselov
    in 2004, however this is apparently debatable.
  • First conceived in 1946. But they didnt believe
    it could be created at room temperature.
  • Graphene as we know it was theoretically
    mentioned as recent as 1984 to describe the
    layers of graphite.
  • The term Graphene was used mainly In working
    with Carbon Nano-tubes.

5
Amazing Physical Properties
  • The strongest material ever measured. Up to 150X
    stronger than the equivalent weight of steel.
  • Pliable as rubber and has the ability to stretch
    up to 120 of its length then recover its
    original shape.
  • Extremely light weight, its said that a single
    sheet of Graphene covering a whole football field
    would weigh less than 1g.

6
Electrical Properties
  • Graphene is classified as a zero-overlap
    semi-metal, which means that either holes or
    electrons are charge carriers.
  • Very high electrical conductivity when exposed to
    an electric field.
  • In a vacuum, it had a mobility that was up to
    250X that of Si. Out conducts copper by a
    thousand times.
  • Effective mass at the Dirac point is zero for
    both electrons and holes.

7
Other Properties
  • Only known substance that is completely
    impermeable to gas.
  • Graphene oxide reportedly has the ability to
    attract radioactive material.
  • Safer creation of Quantum Dots. Reduces the
    price from 1million a kg to 100 a ton.
  • Also has some optical properties that are being
    tested as we speak.
  • Graphene has the ability to transmit up to 98 of
    light.

8
How graphene is created Mechanical Exfoliation
  • Typically involves scotch tape.
  • Stick the tape to a graphite block.
  • Use another piece of tape and stick the two
    sticky sides together. Repeat this process
    20-100x
  • Press the piece of tape with the graphene on a
    substrate.

9
Chemical exfoliation
  • The block graphite is submerged into a solvent.
  • An ultrasound is used to cause a splitting effect
    within the graphite structure.
  • Prolonged exposure causes little platelets to be
    formed.
  • Enriched by a centrifuge.

10
CE via graphene oxide
  • Uses the same process as chemical exfoliation but
    graphene is oxidized.
  • After the CE process, it is then deposited on
    substrate and reduced to parent graphene in some
    fashion.

11
Chemical Vapour Deposition
  • The most common practice in creating graphene
    today.
  • Typically a copper substrate is exposed to a low
    pressure, 1000C annealing process.
  • Methane and Hydrogen gas flows through the
    furnace.
  • Carbon atoms from Methane deposite on the copper,
    creating a continuous graphene sheet.

12
Silicon Carbide
  • A small amount of silicon carbide is placed in a
    box with a hole in it.
  • The box is sealed in a vacuum or argon gas and
    heated to 1500C.
  • Si molecules evaporate from the surface leaving a
    layer of graphene.

13
Graphenes current uses
  • In early 2014 I.B.M announced that it had built
    the first integrated circuit for wireless
    devices.
  • Today a tennis racquet with a graphene layer has
    been manufactured.
  • Graphene is an ingredient to conductive inks for
    printing circuitry.
  • Samsung is reportedly releasing a screen that
    employs Graphene to deliver current to the
    display.

14
Optical Electronics
  • Believed to mainly be used in touchscreens, OLED,
    and LCD.
  • Graphene matches Indium-Tin Oxide performance in
    its basic state.

15
Energy storage
  • Graphene is being experimented in both
    supercapacitor and battery construction.

16
Energy storage cont.
  • Graphene based supercapacitors have potential to
    replace small batteries.
  • Uses the chemical exfoliation discussed earlier.
  • Was able to light LEDs with a two minute charge
    for around twelve hours.

17
Graphene Transistors
  • Clocked at 427 Ghz.
  • Create a false band gap by employing Negative
    resistance.
  • Another type of FET uses dual gate construction.

18
Graphenes future
  • Biomedical Engineering
  • Optical Electronics
  • Ultra-Filtration
  • Composite Materials
  • Photo-Voltaic cells
  • Energy Storage
  • Radioactive Clean-up

19
Challenges Surrounding Graphene
  • Graphene has no bandwidth, which means it cannot
    be shut off.
  • A very hydrophobic material
  • Very expensive and hard to manufacture for most
    companies.
  • When deployed it seemed that the results werent
    duplicated.
  • Graphene is hard to produce in large usable
    sheets. Small flakes are what we use to test
    usually.

20
Conclusion
  • Graphene has many obstacles to work around before
    it can be implemented into todays technology.
  • Researchers are suggesting that its a matter of
    months rather than years for the next graphene
    break through.
  • Graphene has so many amazing properties, so
    expect it to impact many types of technologies.

21
References
  • http//www.sciencedaily.com/releases/2012/09/12091
    0082304.htm
  • De la Fuente, Jesus. www.graphene.com.13 April
    2015
  • Colapinto, John. Graphene may be the most
    remarkable substance ever discovered. But what is
    it for?.The New Yorker, 22 December, 2014.Web.13
    April, 2015
  • Wang, Brian.Graphene Hybrid Supercapacitors
    storing as much as lead acid batteries which is
    six times commercial supercapacitors
    www.nextbigfuture.com 17 April, 2015. Web 20
    April, 2015.
  • Johnson, Dexter. Graphene circuit competes head
    to head with Si technology.www.spectrum.ieee.org
    3 February, 2014.Web.20 April, 2014.
  • Malasarn, Davin. UCLA Researchers develop new
    technique to scale up production of graphene
    micro super capacitors. www.newsroom.ucla.edu.
    19 February, 2013.Web. 20 April, 2015

22
Key Concepts
  • The first 2-D material ever discovered, only
    measuring 1-atom thick.
  • Lightest material ever discovered.
  • Strongest material ever discovered per unit
    weight.
  • Best electrical/thermal conductivity discovered
    at room temperature.
  • Currently does not possess a band-gap like a Si
    gate does.

23
Questions?
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