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 Applications
WHAT 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.

3. BASIC STRUCTURES:
 Fullerenes (0D)
 Carbon Nanotube (1D)
 Graphene (2D)
 Graphite (3D)

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 900-1000°C)
Thin layers of nickel deposited on Si-substrate using an e-beam
evaporator
 The sample heated to 1000°C 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

8. PROPERTIES:
Electronic Properties
 Optical Properties
 Thermal Properties
 Mechanical Properties
 Quantum Hall Effect

9. ELECTRONIC PROPERTIES:
Energy-momentum is linearly related
 Analogous to relativistic particles
 Cannot be described by Schrödinger
equation
 Behave according to Dirac’s equation

10. OPTICAL PROPERTIES:
 Unexpectedly high opacity for an atomic monolayer
 Absorbs 2.3% of the white light
Graphene is photo luminescence
THERMAL 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 Biodevices
LIMITATIONS:
 Reproducibility
 Unable to work as a switch
 Resistivity changes small

13. MAJESTIC FUTURE:
 Advancement in touch screen
 Conductive plastic
 Electric batteries
 Aerospace
 Hydrogen storage

14. THANKS TO ALL….