1. GRAPHENE:AN OVERVIEW OF A WONDER MATERIAL Submitted by
Maliha Khatun Ela Batch- IV MS. Laboratory Department of
Physics
2. WHY WONDER? Unique Structures Exceptional Properties
Futuristic ApplicationsWHAT IS GRAPHENE? Single layer of carbon
packed in hexagonal lattice Consists of sp2 bonded carbon atoms
with C-C distances of 0.142nm Basic structural element for all
other graphitic material In 2010, the Nobel Prize was awarded to
Andre Geim and Konstantin Novoselov.
4. SYNTHESIS: The Scotch Tape Method Thermal Decomposition on
SiC Chemical Vapour Deposition
5. THE SCOTCH TAPE METHOD: Developed by researchers at
Manchester University Cleaving HOPG with a tape Transferred to a Si
wafer Optical microscope image
6. THERMAL DECOMPOSITION ON SiC: SiC heated to high temperature
Removal of Si leaves carbon to rearrange Thickness depends on
annealing time and temperature Expensive process Show electronic
properties
7. CHEMICAL VAPOUR DEPOSITION: Flowing hydrocarbon on a Ni film
(at 900-1000C)Thin layers of nickel deposited on Si-substrate using
an e-beamevaporator The sample heated to 1000C inside a quartz tube
Flowing CH4:H2:Ar mixture Cooling fast the sample to room
temperature Etching nickel layer by using FeCl3 Separating graphene
film Preserve high crystalline quality Observed electrical and
mechanical properties
9. ELECTRONIC PROPERTIES:Energy-momentum is linearly related
Analogous to relativistic particles Cannot be described by
Schrdingerequation Behave according to Diracs equation
10. OPTICAL PROPERTIES: Unexpectedly high opacity for an atomic
monolayer Absorbs 2.3% of the white lightGraphene is photo
luminescenceTHERMAL PROPERTIES:At room temperature thermal
conductivity is 3000-5000 W/mK.
11. MECHANICAL PROPERTIES: Strongest material ever tested
Highest elastic modulus and strength Graphene sheets, held together
by van der Waals forces Band gap of 0.25eV detected under the
highest strain(0.78%)QUANTUM HALL EFFECT: Behave as a semiconductor
after applied electric field At room temperature it shows linear
dispersion relation and has zero effective mass Exhibits both
integer and fractional QHE.
12. APPLICATIONS: Graphene Transistor Graphene Nanoribbons
Transparent Conducting Electrodes Ultracapacitors Graphene
BiodevicesLIMITATIONS: Reproducibility Unable to work as a switch
Resistivity changes small
13. MAJESTIC FUTURE: Advancement in touch screen Conductive
plastic Electric batteries Aerospace Hydrogen storage