Download - 7. Carbon Nanotubes
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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
PEG)
80-90% (70% SWNT
loading) $150/100mg 0.1 grams
P8-SWNT
Water soluble (functionalized with
PABS)
80-90%(30% SWNT
loading) $150/100mg 0.1 grams
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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MWNTs
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
SWNTs
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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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CVD
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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NB:
for metals
n ~ 1
n
o
oT
T
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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)!