Graphene has potential applications in nanotechnology due to its unique properties at the nanoscale. It is the thinnest material known, with high thermal and electrical conductivity. Early attempts to isolate graphene were unsuccessful, but in 2004 researchers developed a "Scotch tape method" to peel off single-atom thick sheets from graphite, revealing graphene's hexagonal structure under an atomic force microscope. Graphene's electronic properties make it a zero-overlap semimetal with high electron mobility, and its lattice structure results in remarkable thermal conduction properties superior to other materials like diamond. These characteristics could enable new technologies if graphene sheets can be effectively manufactured.

1. GRAPHENE,
A route to Nanotechnology

2. Nanotechnology
Manipulation of matter on an
• atomic,
• molecular, and
• supramolecular scale
• Materials reduced to the nanoscale can show
different properties compared to what they
exhibit on a macroscale, enabling unique
applications.

3. Nanotechnology is a technology, which allows to work with substances on
the levels of individual atoms.

4. Nanotechnology

5. Why Graphene?
• thinnest imaginable material
• stiffest known material (stiffer than diamond)
• most stretchable crystal (up to 20% elastically)
• record thermal conductivity (outperforming
diamond)
• lightest charge carriers (zero rest mass)
• longest mean free path at room T (micron range)
• most impermeable (even He atoms cannot squeeze
through)

6. History & attempts
• 1859 Benjamin Collins Brodie lamellar structure
of graphite oxide
• P. R. Wallace in 1947 theory of graphene
• "Nano scaled Graphene Plates” first patents pertaining to
the production of graphene (2002).

10. Chemical Reaction

12. Results in Sludge!!

13. Mechanical Polishing

14. But Not Graphene

15. 2004…..the time came at last!!

17. Scotch Tape Method……..
A McIverist Approach

18. Atomic Force Microscope revealed
their success!!

19. The Periodic Table

20. Electronic structure
C 1s2 2s2 2p2

21. Carbon Allotropes

26. Structure & Stability
• Crystalline allotrophy of carbon with 2-
dimensional hexagonal lattice.
• sp2 hybridization
• Very thin atomic thickness (of 0.345Nm).

28. Electronic properties
• Zero-overlap semimetal

29. Dirac Point

30. Band Gap Variation

31. Eelectron transport
• Very high electrical conductivity
• But very much different from metals.
• Transport dominated by two modes.
• ballistic and temperature independent
• thermally activated.

32. Eelectron transport
• Mobility 10×106 times greater than copper.
• displays remarkable electron mobility at room
temperature, with reported values in excess of
15000 cm2⋅V−1⋅s−1
• Scattering by graphene's acoustic phonons
intrinsically limits room temperature mobility to
200000 cm2⋅V−1⋅s−1,
• resistivity of graphene sheets would be 10−6 Ω⋅cm.
This is less than the resistivity of silver,

33. Thermal properties
 Graphene is a perfect thermal conductor
 Its thermal conductivity > 5000 W/m/K at
room temperature
 Graphite shows a thermal conductivity
about 5 times smaller (1000 W/m/K)
 The ballistic thermal conductance of
graphene is isotropic, i.e. same in all
directions

34. Lattice waves
• The atoms in a crystal are restricted to
small movements around the points
they occupy in the crystal lattice.

35. Crystal: Al , Symmetry: Cubic.

36. At high frequencies ω is then no
longer proportional to q

37. Phonon
 a quantum of energy
 trying to control the way heat moves through
solids,
better to think of it as a flow of particles
 Low-frequency vibrations correspond to
sound, while higher frequencies correspond to
heat

38. phonon
 Acoustic phonons are the main heat
carriers
 The unique nature of two-dimensional
phonontransport translates into unusual
heat conduction in graphene .
 The phonon andthermal properties of
nanostructures are substantially different
from those of bulk crystals

39. Measurements of heat conduction
• The
first measurements of
heat conduction in
graphene [35–40]
were carried out at UC
Riverside in 2007
•
optothermal Raman
measurement
technique.

41. Comparison
of different
thermal
conductivity

42. Application & Future