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

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??

Its None another than

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

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.

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…

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

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

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.

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.

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

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.

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

Extra Ordinary Electronic

Applications of Graphene:

Bioelectric Sensor

Optical Electronic Properties

Photovoltaic cell

Ultra Filtration

Energy Storage

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

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.

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.

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.