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.

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 900-1000C)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

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 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

14. THANKS TO ALL.