Presented By:
Aniruddha.K.Purohit

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Introduction
We can define nanocarbon as materials built at nanometer scale from sp2 hybridized carbon atoms similar to that of graphite.
This bonding structure, which is stronger than the sp3 bonds found in diamonds, provides the molecules with their unique strength.
Carbon nanotubes are wires of pure carbon with nanometer diameters and lengths of many microns.  
They are the allotrope of carbon.
They take the form of cylindrical carbon molecules and have novel properties .
Which make them potentially useful in a wide variety of applications in nanotechnology, electronics, optics, and other fields of materials science.
They exhibit extraordinary strength and unique electrical properties, and are efficient conductors of heat.
They are hollow cylinders composed of one or more concentric layers of carbon atoms in a honeycomb lattice arrangement.
History
C-60 clusters were the 3rd allotrope of carbon.
Japanese scientist Sumio Iijima discovered fullerene-related carbon nanotubes in 1991.
In the form of thread lying in a smear of sooth.
The tubes contained at least two layers, often many more, and ranged in outer diameter from about 3 nm to 30 nm. They were invariably closed at both ends.
It is important to note, however, that nasnoscale tubes of carbon, produced catalytically, had been known for many years before Iijima’s discovery.
The main reason why these early tubes did not excite wide interest is that they were structurally rather imperfect, so did not have particularly interesting properties
Recent research has focused on improving the quality of catalytically-produced nanotubes.
Types
Several types of nanotubes exist; but they can be divided in two main categories:
single-walled (SWNT) :individual cylinders of 1-2nm.
multi-walled (MWNT):are collections of several concentric graphene cylinders
Structure
Armchair( n, n)
Zig zag(n,0)
Chiral( n,m)
Properties
High mechanical stability and chemical inertness.
Carrier transport is 1-D.
Electrostatic behavior is different.
All chemical bonds of C atom are satisfied.
Thermal stabilty:3000 W/mK
Maximum strain:10% higher than any other material.
Very high current carrying capacity.
Excellent field emitter.
Processing
Arc Discharge:
Laser ablation:
Chemical Vapour Deposition:
CNT’s in Electronics
CNTFET’s
Several types of devices can be made using SWCNT’s instead of conventional semiconductor such as silicon..
Quantum mechanical tunneling becomes important as the length of the transistor channel and thickness of gate insulator decreases.
This results in high leakage current which damages the transistor as a switch.
While scaling the width of metallic wire should also be scaled which increases the resistance.
Why we choose nanotubes?
SWCNT’s are one dimensional systems , so they do not allow the small angle scattering of electrons or holes.
There is no electromigration and metallic nanotubes carry current densities 2-3 orders of magnitude higher than metals such as copper or aluminum.
CNT Diode
Some of the applications:
Micro-electronics / semiconductors
Controlled Drug Delivery/release
Field emission flat panel displays
Field Effect transistors
Single electron transistors
Nano lithography
Nano electronics
Doping
Nano balance
Nano tweezers
Data storage
Magnetic nanotube
Nanogear
supercapacitor
Conclusion
Carbon nanotubes are the next step in miniaturizing electronic circuits, replacing silicon transistors and diodes, which are fast reaching the theoretical limits of size and speed of operation.
Using CNTs, nanochips can be made with entire circuits on it. Ideal diodes can be made from CNTs, resulting in highly efficient electronic circuits. Further, CNTs have a number of other uses other than in the electronic industry, as seen here.