7. Carbon Nanotubes

transcript

anjanachuchai2102-584 Intro to N

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7. Carbon Nanotubes

1. Overview: Global status |market | price

2. Types• MWNT / SWNT

• zig-zag / armchair / chiral

3. Properties• electrical

• others

4. Synthesis• arc discharge / laser ablation / CVD

5. Applications

• active: diode / FET

• passive: (transparent) conductor, filament

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ITRS2009

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Scanning Electron-Microscopy

(SEM) image of a CNT attached

to a cantilever tip.

Seldon Labs' nanotube-

filter provides reliably

clean water, nearly free of

bacteria and viruses

(Courtesy of Seldon Labs).

Nissan's X-Trailsport-utility

vehicle has CNT-reinforced

bumpers (Courtesy of Nissan).

NASA's Morphing Glider will have

flexible CNT wings that move like

a hawk's. The wings will curl,

twist, extend and

twitch.(Courtesy of NASA)

http://www.ahwahneetech.com/technology/index.htm

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Overview: CNT Global status

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The current price schedule for our

AP-Grade, single-walled carbon

nanotube (SWNT) material is:

Quantity Price

More than 100 grams $60/g

50-100 grams $80/g

Less than 50 grams $100/g

PRODUCT DESCRIPTION

CARBONACEOUS

PURITY* PRICE** MINIMUM ORDER

AP-SWNT As prepared 40-60% $50/g 2 grams

P2-SWNT Purified, low functionality 70-90% $400/g 0.5 grams

P3-SWNT Purified, high functionality 80-90% $400/g 0.5 grams

P5-SWNT

Organic soluble (functionalized

with ODA)

80-90%(50% SWNT

loading) $150/100mg 0.1 grams

P7-SWNT

Water soluble (functionalized with

80-90% (70% SWNT

P8-SWNT

Water soluble (functionalized with

80-90%(30% SWNT

18 July 07

Overview: CNT Prices

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7. Carbon Nanotubes

1. Overview

2. Types

• Allotropes of Carbon

• MWNT / SWNT

• zig-zag / armchair / chiral

3. Properties

4. Synthesis

5. Applications

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Allotropes of Carbon

Some allotropes of carbon: a) diamond; b) graphite; c) lonsdaleite; d–f)

fullerenes (C60, C540, C70); g) amorphous carbon; h) carbon nanotube.

http://upload.wikimedia.org/wikipedia/commons/f/f8/Eight_Allotropes_of_Carbon.png

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M. Monthioux, "Who should be given the credit for the discovery of carbon nanotubes?“, CARBON 44: 1621 (2006).

Discovery still in dispute (see article below). But

usually (mis-)credit Iijima who published TEM

image of MWNT in 1991.

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Single-wall nanotubes

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7. Carbon Nanotubes

1. Global status and market

2. Types

3. Properties

• electrical

• others

4. Synthesis

5. Applications

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Armchair

Zig-zag

Because of the symmetry and unique electronic structure of graphene, the

structure of a nanotube strongly affects its electrical properties. For a

given (n,m) nanotube, if n - m is a multiple of 3, then the nanotube is

metallic, otherwise the nanotube is a semiconductor.

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significantly reduce electromigration

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~$400-700/g in 2005

as-produced arc discharge SWNTs for ~$50-100/g in 2007

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7. Carbon Nanotubes

1. Global status and market

2. Types

3. Properties

4. Synthesis

• arc discharge / laser ablation / CVD

5. Applications

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http://students.chem.tue.nl/ifp03/synthesis.html

In 1992 Thomas Ebbesen and Pulickel M. Ajayan

of the NEC Fundamental Research Laboratory in

Tsukuba, Japan, published the first method for

making macroscopic quantities of nanotubes. It

is almost Frankensteinian in its design: wire

two graphite rods to a power supply, place

them millimeters apart and throw the switch.

As 100 amps of juice spark between the rods,

carbon vaporizes into a hot plasma

(right).Some of it recondenses in the form of

nanotubes.

Typical yield: Up to 30 percent by weight

Advantages: High temperatures and metal

catalysts added to the rods can produce both

single-walled and multiwalled nanotubes with

few or no structural defects.

Limitations: Tubes tend to be short (50

microns or less) and deposited in random sizes

and directions.

Arc Discharge

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Morinubo Endo of Shinshu University in Nagano, Japan,

was the first to make nanotubes with this method, which

is called chemical vapor deposition (CVD). This recipe

is also fairly simple. Place a substrate in an

oven,heat to 600 degrees Celsius and slowly add a

carbon-bearing gas such as methane. As the gas

decomposes, it frees up carbon atoms, which can

recombine in the form of nanotubes. Jie Liu and his

colleagues at Duke University recently invented a

porous catalyst that they claim can convert almost all

the carbon in a feed gas to nanotubes. By printing

patterns of catalyst particles on the substrate,

Hongjie Dai and his colleagues at Stanford University

have been able to control where the tubes form (left)

and have been working to combine this controlled growth

with standard silicon technology.

Typical yield: 20 to nearly 100 percent

Advantages: CVD is the easiest of the three methods to

scale up to industrial production. It may be able to

make nanotubes of great length, which is necessary for

fibers to be used in composites.

Limitations: Nanotubes made this way are usually

multiwalled and are often riddled with defects. As a

result, the tubes have only one tenth the tensile

strength of those made by arc discharge.

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Laser Ablation

Richard Smalley and his co-workers at

Rice University were blasting metal with

intense laser pulses to produce fancier

metal molecules when the news broke about

the discovery of nanotubes. They swapped

the metal in their setup for graphite

rods and soon produced carbon nanotubes

by using laser pulses instead of

electricity to generate the hot carbon

gas from which nanotubes form (left).

Trying various catalysts, the group hit

on conditions that produce prodigious

amounts of single-walled nanotubes.

Typical yield: Up to 70 percent

Advantages: Produces primarily single-

walled nanotubes, with a diameter range

that can be controlled by varying the

reaction temperature.

Limitations: This method is by far the

most costly, because it requires very

expensive lasers.

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Metal catalysts as nucleation centres

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7. Carbon Nanotubes

1. Overview

2. Types

3. Properties

4. Synthesis

5. Applications

• active: FET / SET / LED

• passive: (transparent) conductor, filament

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Vsd = 5 mV

as-grown CNTs p-type

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Intramolecular logic gates

Potassium evaporation through window opened by EBL.

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Electronic devices based on purified

carbon nanotubes grown by high-pressure

decomposition of carbon monoxide, Nature

Materials 4, 1-4 (01 Aug 2005)

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200 nm 20 nm

AFM tip in tapping mode.

Metallic NT used.

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electron injection

hole injection

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CNT field emission lamps arrayed

in a 5-by-7 matrix. (Courtesy of

Noritake Co. Ltd.)

http://www.noritake-itron.jp/japanese/technology/nano.htm

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for metals

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Schematic illustration of a CNT-based

field emission display

25” CNT TV from

Applied Nanotech, a

subsidiary of Nano-

Proprietary, Inc.

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Vertical nanotube clusters

A cold-cathode lighting-

tube element with a

carbon nanotube emitter

(Ahwahnee Technology).

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densification for interconnects

Side view of a CNT bundle end before

(left) and after (right) densification

process.

Recipe 2 CNT bundles before (left) and

after (right) densification.

CNTs Attractive Alternative for Interconnects Semiconductor International, 5/1/2007

109 A/cm2

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Conclusions

• CNTs are a new class of materials with

unique electrical, mechanical, thermal

properties

• Applications in electronics include FETs,

logic gates, LEDs, flat-panel displays,

light bulbs

• Graphene nanoribbons (GNRs)!

7. Carbon Nanotubes

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