graphene electronic properties (1)
TRANSCRIPT
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Term Paper PresentationNTY320:: Applied Nanotechnology
Topic : Graphene Electronic Properties
Submitted to:
Mr. Amit Sachdeva
Deptt. Of Nanotechnology
Lovely Professional University
Submitted by:
Vir Sapan Pratap Anand
11202530
Section : B1205
Roll No. : A10
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Ever thought of a non metal or
semiconductor with zero band Gap?
Ever thought of 2-D Compounds ?
Ever thought of a material with
tensile strength of 130GPa and even
you can pick it like a child’s play..?
Ever thought of a conducting material
that can transmit 97.7% of light ??
Ever thought of a conducting
material with 20 times stretchable
capacity of its length??
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Its None another than
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Graphene : Electronic Properties
Topics To be discussed
Introduction to Graphene
Why Graphene is So special?
Properties of Graphene
More about Electronic properties
Hall Effect
Extraordinary Properties, Extraordinary Applications
Summary
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Graphene : A brief
introduction It is a 2-D allotrope of Carbon at
atomic scale with hexagonal lattice.
Graphene – a combination of “Graph”
and suffix “-ene” named by Hanns
peter Boehm in 1962.
It has atomic thickness of 0.345nm
and 200 times stronger than steel.
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Why So Special ??
Sp2 Hybridization
0.345nm thickness.
Atoms 1.42 A apart.
These properties enable graphene to be
extraordnary in terms of:
1. Strength
2. Electricity
3. Heat Conduction
And many More…
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Properties of Graphene:
Chemical property : Highest ratio of
edge atoms of any allotrope, defects
within a sheet increase its reactivity.
Optical Property: Able to transmit
97.7% of light; reflectance and
transmittance studied as function of v,
temp. and Carrier density.
High Conductivity of Graphene :
1500-2500 W/mK
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Mechanical Properties of
Graphene
1. Tensile strength = 130
GPa
Young’s Modulus = 1 TPa
Weight of 1 sq. meter
Graphene sheet =
any Guesses ?
Only 0.77 mg
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Could 2-D compounds exist ?
Till 2004, no one believed so.
Due to their thermal instability when
separated
Graphene made it POSSIBLE.
Carbon – Carbon bonds in Graphene
are so small and strong that they
prevent thermal fluctuations from
destroying it.
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Electronic Properties of
Graphene: Carbon – 6 electrons : 2 in inner shell
and 4 in outer shell which are
available for chemical bonding.
But in Graphene, each atom
connected to other three C atoms.
Which leaves one e- freely available in
3rd Dimension for e- conduction (pi
electron)
They overlap and help in C-C bond
formation in graphene.
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Brillouin Zone and Dirac
Points: Brillouin Zone: In Solid State
Physics, it is a uniquely defined
primitive cell whose boundaries are
given by planes related to points on
the reciprocal lattice.
Dirac Points: The electrons and
holes and the six corners of Brillouin
zone are called Dirac Points
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Hall effect:
Production of a voltage difference
(the Hallvoltage) across an electrical
conductor, transverse to an electric
current in the conductor and a
magnetic field perpendicular to the
current.
It was discovered by Edwin Hall in
1879.
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Quantum Hall Effect
Observed in 2-D e- systems
Subjected to low temperatures
In strongly applied Magnetic field
Hall conductance can be studied
I = Channel current, e = elementary
charge
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Extra Ordinary Electronic
Applications of Graphene:
Bioelectric Sensor
Optical Electronic Properties
Photovoltaic cell
Ultra Filtration
Energy Storage
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Applications continued…
1. Biological Sensing Devices : due
to large surface area and high
conductivity, it can be used to
monitor Glucose levels, haemoglobin
levels, cholesterol level and even
DNA Sequencing.
2. Optical Electronics: As it Transmits
97.7% of light and has high
conductivity, It can be used in LCDs,
Org. LEDs
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Applications Continued…
3. Ultrafiltration: Pore size of 5nm,
graphene can be employed in water
filtration, desalination system and
viable biofuel creation.
4. Photovoltaic cell: absorbs a
photon, generates multiple electrons.
Able to work in all wavelengths, can
be used to power our homes through
curtains and to recharge mobile
phones.
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Applications Continued:
Energy Storage: - Can be used to make super
capacitors.
- Able to charge very quickly.
- Could be used in high energy
applications such as electric vehicles,
laptops, smart phones, tablets, PCs at
significantly low size and weight.
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Summary
1. Graphene is single atom thin sheet of Carbon
2. It has extraordinary mechanical, optical and electronic properties.
3. C-C bonds are so small and strong and give it 2-D Structure
4. Electronic Properties dictated by Pi-Orbitals
5. Quantum Hall effect used to study voltage and conductance
6. It has variety of applications in biosensors, optical elctronics, energy storage, photovoltaic cell etc.
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