Graphene

1
Graphene

• Graphene physically acts as a 2-Dimensional
  material. This leads to many properties that are
  electrially beneficial, such as high electron
  moblity and lowered power usage. Graphene is
  currently in its infant stages and is undergoing
  many applications and studies.
• Jared Johnson Jason Peltier
• April 30th

2
Introduction

• What is Graphene
• Discovery
• Electrical Properties
• Mechanical Strength
• Optical Properties
• Applications
• Devices

3
What is Graphene

• 2-dimensional, crystalline allotrope of carbon
• Allotrope property of chemical elements to exist
  in two or more forms
• Single layer of graphite
• Honeycomb (hexagonal) lattice

http//upload.wikimedia.org/wikipedia/commons/thum
b/9/9e/Graphen.jpg/750px-Graphen.jpg
4
Graphene vs Other Allotropes

• Graphene - Top Left
• Graphite - Top Right
• Nanotube - Bottom Left
• Fullerene - Bottom Right

http//graphene.nus.edu.sg/content/graphene
5
Discovery

• Studies on graphite layers for past hundred years
• Graphene theory first explored by P.R. Wallce
  (1947)
• Andre Geim Kontantin Novoselov Nobel Peace
  Prize (2010)
• Physics observed using TEM

http//powerlisting.wikia.com/wiki/FileGraphite.j
pg
http//www.telegraph.co.uk/science/science-news/80
43355/Nobel-Prize-for-Physics-won-by-Andre-Geim-an
d-Konstantin-Novoselov.html
6
Electronic Structure

• First Brillouin Zone (red)
• Second Brillouin Zone (yellow)
• Six corners of first Brillouin zone called Dirac
  points (also called K points)
• Electrons and holes called Dirac fermions

http//www.doitpoms.ac.uk/tlplib/brillouin_zones/z
one_construction.php
7
Electronic Structure

• Dirac Points are the transition between the
  valence band and the conduction band
• The six Dirac points can be divided into to two
  in-equivalent sets of three (K and K'),
  represented by the black and white dots on part
  (a)
• The points within each set are all equivalent
  because they can reach each other by reciprocal
  lattice vectors
• Part (b) shows that the dispersion relation close
  to the K points looks like the energy spectrum of
  massless Dirac particles

http//ej.iop.org/images/0034-4885/75/5/056501/Ful
l/rpp342429f06_online.jpg
8
Electrical Properties

• The Fermi level can be changed by doping to
  create a material that is better at conducting
  electricity
• Experimental graphene's electron mobility is
  15,000 cm2/(Vs) and theoretically potential
  limits of 200,000 cm2/(Vs)
• Graphene electrons are like photons in mobility
  due to lack of effective electron and hole mass
• These charge carriers are able to travel
  sub-micrometer distances without scattering

9
Mechanical Strengths

• Bond length is .142 nm long very strong bond
• Strongest material ever discovered
• ultimate tensile strength of 130 gigapascals
  compared to 400 megapascals for structural steel
• Very light at 0.77 milligrams per square metre,
  paper is 1000 times heavier
• Single sheet of graphene can cover a whole
  football field while weighing under 1 gram
• Also, graphene is very flexible, yet brittle
  (preventing structural use)

10
Optical Properties

• Absorbs 2.3 white light
• Optical electronics absorb lt10 white light
• Highly conductive
• Strong and flexible

http//en.wikipedia.org/wiki/FileGraphene_visible
.jpg
Photograph of graphene in transmitted light.
11
Other Applications

• OLED Techonologies
• Body Armour
• Lightweight Aircraft/vehicles
• Photovoltaics
• Superconductor/battery
• Filtration
• http//www.graphenea.com/pages/graphene-uses-appli
  cations.U1c1hFVdV8E

12
Devices
http//www.tgdaily.com/general-sciences-features/6
1058-team-uses-graphene-film-to-distil-vodka
http//www.simplifysimple.com/index.php?newsnid1
5_The-new-look-of-phones
http//en.wikipedia.org/wiki/OLED
13
Summary Conclusion

• Graphene, a singular layer of graphite, has been
  discovered to have unique properties. The high
  mobility and ability to travel short distances
  without scattering makes it one of the best
  materials for electrical applications. Graphene's
  mechanical and optical properties also allow its
  use to go beyond electrical applications.

14
References

1. "Allotrope." Wikipedia. Wikimedia Foundation, 16
   Apr. 2014. Web. 17 Apr. 2014. lthttp//en.wikipedia
   .org/wiki/Allotropegt.
2. Cooper, Daniel R. "Experimental Review of
   Graphene." Hindawi Publishing Corporation, 3 Nov.
   2011. Web. 16 Apr. 2014. lthttp//www.hindawi.com/j
   ournals/isrn/2012/501686/gt.
3. De La Fuente, Jesus. "Graphene." Graphenea. Web.
   26 Apr. 2014. lthttp//www.graphenea.com/pages/grap
   hene.U1xxufldWSogt.
4. Geim, Andre. "Nobel Lecture." Nobel Prize, 8 Dec.
   2010. Web. 18 Apr. 2014. lthttp//www.nobelprize.or
   g/mediaplayer/index.php?id1418gt.
5. "Graphene." Wikipedia. Wikimedia Foundation, 16
   Apr. 2014. Web. 17 Apr. 2014. lthttp//en.wikipedia
   .org/wiki/graphenegt.
6. Neamen, Donald A. Semiconductor Physics and
   Devices Basic Principles. New York, NY
   McGraw-Hill, 2012. Print.
7. Roos, Michael. "Intermolecular vs
   Moleculesubstrate Interactions." Beilstein
   Journal of Nanotechnology 2012.2, 365-73. Web. 15
   Apr. 2014. lthttp//www.beilstein-journals.org/bjna
   no/single/articleFullText.htm?publicId2190-4286-2
   -42gt.
8. "Graphene." NUS Graphene Research Centre.
   National University of Singapore, n.d. Web. 28
   Apr. 2014. lthttp//graphene.nus.edu.sg/content/gra
   phenegt.

15
Last Slide

• Graphite had been studied for over a hundred
  years but Geim and Novoselov found how to isolate
  it to be graphene and some applications for its
  use
• The reason graphene is such a beneficial material
  is due to its 2D like nature and short/strong
  bonds
• It has a super high conductivity and an electron
  mobility of 15,000 cm2/(Vs)
• It is the strongest material ever discovered,
  however its brittle nature cannot be used
  structurally (only to help reinforce)
• One of the most common current uses of graphene
  is in OLEDs