M' Meyyappan

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Nanotechnology Advantages and Applications
M. Meyyappan Center for Nanotechnology NASA Ames
Research Center Moffett Field, CA 94035 email
mmeyyappan_at_mail.arc.nasa.gov
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What is Nanotechnology?
Nanotechnology is the creation of
USEFUL/FUNCTIONAL materials, devices and systems
(of any size) through control/manipulation of
matter on the nanometer length scale and
exploitation of novel phenomena and properties
which arise because of the nanometer length scale
Physical Chemical Electrical Mechanical
Optical Magnetic
Source K.J. Klabunde, 2001
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Unique Properties of Nanoscale Materials

• Quantum size effects result in unique mechanical,
  electronic, photonic, and magnetic properties of
  nanoscale materials
• Chemical reactivity of nanoscale materials
  greatly different from more macroscopic form,
  e.g., gold
• Vastly increased surface area per unit mass,
  e.g., upwards of 1000 m2 per gram
• New chemical forms of common chemical elements,
  e.g., fullerenes, nanotubes of carbon, titanium
  oxide, zinc oxide, other layered compounds

Source Clayton Teague, NNI
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NNI Program Component Areas (PCAs)

• Fundamental Nanoscale Phenomena and Processes
• Nanomaterials
• Nanoscale Devices and Systems
• Instrumentation Research, Metrology, and
  Standards for Nanotechnology
• Nanomanufacturing
• Major Research Facilities and
  Instrumentation Acquisition
• Societal Dimensions

Source Clayton Teague, NNI
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Nanotechnology R D
and Related
Nanomaterials
Applications
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Various Nanomaterials and Nanotechnologies
Nanocrystalline materials Nanoparticles Nano
capsules Nanoporous materials Nanofibers Nan
owires Fullerenes Nanotubes Nanosprings Na
nobelts Dendrimers
Molecular electronics Quantum dots NEMS,
Nanofluidics Nanophotonics, Nano-optics Nanoma
gnetics Nanofabrication Nanolithography Nano
manufacturing Nanomedicine Nano-bio
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Impact of Nanotechnology
Information Technology - Computing, Memory
and Data Storage - Communication Materials
and Manufacturing Health and
Medicine Energy Environment Transportatio
n National Security Space exploration
Nanotechnology is an enabling technology
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Ability to synthesize nanoscale building blocks
with control on size, composition etc.
further assembling into larger structures
with designed properties will revolutionize
materials manufacturing - Manufacturing metals,
ceramics, polymers, etc. at exact shapes without
machining - Lighter, stronger and
programmable materials - Lower failure rates and
reduced life-cycle costs - Bio-inspired
materials - Multifunctional, adaptive
materials - Self-healing materials
Challenges ahead - Synthesis, large scale
processing - Making useful, viable
composites - Multiscale models with predictive
capability - Analytical instrumentation
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Carbon Nanotubes Nanostructured
Polymers Optical fiber performs through
sol-gel processing of nanoparticles Nanoparticl
es in imaging systems Nanostructured
coatings Ceramic Nanoparticles for netshapes
Source IWGN Report
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More Examples of Nanotech in Materials and
Manufacturing
Nanostructured metals, ceramics at exact shapes
without machining Improved color printing
through better inks and dyes with
nanoparticles Membranes and
filters Coatings and paints (nanoparticles)
Abrasives (using nanoparticles) Lubricants C
omposites (high strength, light
weight) Catalysts Insulators
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Nanoelectronics and Computing
Past Shared computing thousands of people
sharing a mainframe computer
Present Personal computing
Future Ubiquitous computing
thousands of computers sharing each and everyone
of us computers embedded in walls, chairs,
clothing, light switches, cars. characterized
by the connection of things in the world with
computation.
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There is at least as far to go (on a
logarithmic scale) from the present as we have
come from ENIAC. The end of CMOS scaling
represents both opportunity and
danger. -Stan Williams, HP A few more
CMOS generations left but cost of building fabs
going up faster than sales. Physics has room
for 109x current technology based on 1
Watt dissipation, 1018 ops/sec no clear ways to
do it! - Molecular nanoelectronics ? -
Quantum cellular automata ? - Chemically
synthesized circuits ? Self assembly to reduce
manufacturing costs, defect tolerant
architectures may be critical to future
nanoelectronics
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Quantum Computing - Takes advantage of
quantum mechanics instead of being limited by
it - Digital bit stores info. in the form of
0 and 1 qubit may be in a superposition
state of 0 and 1 representing both
values simultaneously until a measurement is
made - A sequence of N digital bits can
represent one number between 0 and 2N-1 N
qubits can represent all 2N numbers
simultaneously
Carbon nanotube transistors by several
groups Molecular electronics Fabrication of
logic gates from molecular switches using
rotaxane molecules Defect tolerant
architecture, TERAMAC computer by HP
architectural solution to the problem of
defects in future molecular electronics
- Stan Williams, HP
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Expected Nanotechnology Benefits in Electronics
and Computing
Processors with declining energy use and cost
per gate, thus increasing efficiency of computer
by 106 Higher transmission frequencies and
more efficient utilization of optical spectrum
to provide at least 10 times the bandwidth
now Small mass storage devices multi-tera bit
levels Integrated nanosensors collecting,
processing and communicating massive amounts
of data with minimal size, weight, and power
consumption Quantum computing Display
technologies
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Expanding ability to characterize genetic
makeup will revolutionize the specificity of
diagnostics and therapeutics - Nanodevices
can make gene sequencing more efficient Effe
ctive and less expensive health care using remote
and in-vivo devices
New formulations and routes for drug
delivery, optimal drug usage More durable,
rejection-resistant artificial tissues and
organs Sensors for early detection and
prevention
Nanotube-based biosensor for cancer diagnostics
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DNA microchip arrays using advances for IC
industry Gene gun that uses nanoparticles
to deliver genetic material to target
cells Semiconductor nanocrystals as
fluorescent biological labels
Source IWGN Report
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Energy Production and Utilization
Energy Production - Clean, less expensive
sources enabled by novel nanomaterials and
processes - Improved solar cells Energy
Utilization - High efficiency and durable home
and industrial lighting - Solid state
lighting can reduce total electricity
consumption by 10 and cut carbon emission
by the equivalent of 28 million tons/year
(Source Al Romig, Sandia Lab) Materials
of construction sensing changing conditions and
in response, altering their inner structure
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Benefits of Nano in the Environment Sector
Nanomaterials have a large surface area. For
example, single-walled carbon nanotubes show
1600 m2/g. This is equivalent to the size of a
football field for only 4 gms of nanotubes. The
large surface area enables - Large adsorption
rates of various gases/vapors - Separation of
pollutants - Catalyst support for conversion
reactions - Waste remediation Filters
and Membranes - Removal of contaminants
from water - Desalination Reducing auto
emissions, NOx conversion - Rational design of
catalysts
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Benefits of Nanotechnology in Transportation
More efficient catalytic converters Thermal
barrier and wear resistant coatings Battery,
fuel cell technology Improved
displays Wear-resistant tires High
temperature sensors for under the hood novel
sensors for all-electric vehicles High
strength, light weight composites for increasing
fuel efficiency
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Improved collection, transmission, protection
of information Very high sensitivity, low
power sensors for detecting
chem/bio/nuclear threats Light weight
military platforms, without sacrificing
functionality, safety and soldier
security - Reduce fuel needs and
logistical requirements Reduce carry-on weight
of soldier gear - Increased functionality
per unit weight
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Why Nanotechnology at NASA?
Advanced miniaturization, a key thrust area to
enable new science and exploration
missions - Ultrasmall sensors, power sources,
communication, navigation, and propulsion
systems with very low mass, volume and
power consumption are needed Revolutions
in electronics and computing will allow
reconfigurable, autonomous, thinking
spacecraft Nanotechnology presents a whole new
spectrum of opportunities to build device
components and systems for entirely new space
architectures - Networks of ultrasmall
probes on planetary surfaces - Micro-rover
s that drive, hop, fly, and
burrow - Collection of microspacecraft
making a variety of measurements
Europa Submarine
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Carbon Nanotube
CNT is a tubular form of carbon with diameter as
small as 1 nm. Length few nm to microns. CNT
is configurationally equivalent to a two
dimensional graphene sheet rolled into a tube
(single wall vs. multiwalled).
See textbook on Carbon Nanotubes Science and
Applications, M. Meyyappan, CRC Press, 2004.
CNT exhibits extraordinary mechanical properties
Youngs modulus over 1 Tera Pascal, as stiff as
diamond, and tensile strength 200 GPa. CNT can
be metallic or semiconducting, depending on
(m-n)/3 is an integer (metallic) or not (semicon).
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CNT Properties
The strongest and most flexible molecular
material because of C-C covalent bonding and
seamless hexagonal network architecture Strengt
h to weight ratio 500 times greater than Al,
steel, titanium one order of magnitude
improvement over graphite/epoxy Maximum
strain 10 much higher than any
material Thermal conductivity 3000 W/mK in
the axial direction with small values in the
radial direction Very high current carrying
capacity Excellent field emitter high aspect
ratio and small tip radius of curvature are
ideal for field emission Other chemical groups
can be attached to the tip or sidewall (called
functionalization)
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CNT Applications
Sensors, Bio, NEMS CNT based microscopy AFM,
STM Nanotube sensors bio,
chemical Molecular gears, motors,
actuators Batteries (Li storage), Fuel Cells,
H2 storage Nanoscale reactors, ion
channels Biomedical - Nanoelectrodes for
implantation - Lab on a chip - DNA sequencing
through AFM imaging - Artificial
muscles - Vision chip for macular degeneration,
retinal cell transplantation
Electronics CNT quantum wire
interconnects Diodes and transistors for
computing Data Storage Capacitors Field
emitters for instrumentation Flat panel
displays
Challenges
Challenges
Controlled growth Functionalization
with probe molecules, robustness Integration,
signal processing Fabrication techniques
Control of diameter, chirality Doping,
contacts Novel architectures (not CMOS
based!) Development of inexpensive
manufacturing processes
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CNT Synthesis
CNT has been grown by laser ablation (pioneered
at Rice University) and carbon arc process
(NEC, Japan) - early 90s. - SWNT, high
purity, purification methods
CVD is ideal for patterned growth (electronics,
sensor applications) - Well known technique
from microelectronics - Hydrocarbon
feedstock - Growth needs catalyst
(transition metal) - Numerous
parameters influence CNT growth (temperatur
e, choice of feedstock, H2 and
other diluents, choice of catalyst and
preparation)
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CNTs on Patterned Substrates
L. Delzeit et al., Chem. Phys. Lett., Vol. 365,
p. 368 (2001) J. Phys. Chem. B, Vol. 106, p.
5629 (2002).
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Plasma Reactor for CNT Growth
Certain applications such as nanoelectrodes,
biosensors would ideally require individual,
freestanding, vertical (as opposed to towers or
spaghetti-like) nanostructures The high
electric field within the sheath near the
substrate in a plasma reactor helps to grow such
vertical structures dc, rf, microwave,
inductive plasmas (with a biased
substrate) have been used in PECVD of such
nanostructures
Cassell et al., Nanotechnology, 15 (1), 2004
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CNT in Microscopy
Atomic Force Microscopy is a powerful technique
for imaging also CD metrology, nanomanipulation,
as platform for sensor work, nanolithography... C
onventional silicon and other tips wear out
quickly. CNT tip is robust, offers amazing
resolution.
2 nm thick Au on Mica imaged with SWNT
Simulated Mars dust
Written using multiwall tube
Nguyen et al., Nanotechnology, 12, 363 (2001)
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MWNT Scanning Probe
Profilometry in Semiconductor Manufacturing
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CNT Based Biosensors
Probe molecules for a given target can be
attached to CNT tips for biosensor
development Electrochemical approach
requires nanoelectrode development using
PECVD grown vertical nanotubes The signal can
be amplified with metal ion mediator
oxidation catalyzed by Guanine.
High specificity Direct, fast
response High sensitivity Single molecule
and cell signal capture and detection
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Fabrication of Genechip

• Potential applications
• Lab-on-a-chip applications
• Early cancer detection
• Infectious disease detection
• Environmental monitoring
• Pathogen detection

30 dies on a 4 Si wafer
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Single-Walled Carbon Nanotubes For Chemical
Sensors
Applications Industrial Toxic Chemicals,
Safety Explosive Detection Earth
Observation Leak Detection
Single Wall Carbon Nanotube
Every atom in a single-walled nanotube is on the
surface and exposed to environment Charge
transfer or small changes in the
charge-environment of a nanotube can cause
drastic changes to its electrical
properties Monitoring the change in conductivity
forms the basis for sensing
32-channel sensor chip
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Various Inorganic Nanowires
(INWs)
All these have been grown as 2-d thin films in
the last three decades Current focus is to
grow 1-d nanowires
Down to 0.4 eV
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Vertically-Aligned Nanowires for Device
Fabrication
Germanium Nanowires
ZnO Nanowires
P. Nguyen et al., Advanced Materials, Vol. 17, p.
549 (2005).
H.T. Ng et al., Science, Vol. 300, p. 2149 (2003).
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Why 1-D Phase-Change Nanowire?

• Low Thermal Energy for Programming
• Reduced melting point at 1-D
• Reduced programmable element volume
• Reduced activation energy at 1-D
• Device Scalability
• Ultra-low current / voltage / power operation
• Reduced thermal interference between neighboring
  memory cells

Top electrode
Bottom electrode
2-D Thin film PRAM
1-D Nanowire PRAM
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GeTe Nanowires Melting Experiment and In-Situ
Monitoring by TEM
Liquid GeTe
In-situ Tm measurement of GeTe nanowire under TEM
image monitoring (a) The GeTe nanowire is under
room temperature. (b) The GeTe nanowire is heated
up to 400?C when the nanowire is molten and its
mass is gradually lost through evaporation. The
remaining oxide shell can be seen from the image.
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GeTe Nanowires Melting Point
Tm of bulk GeTe 725oC
46 reduction!
Tm of GeTe nanowires 390oC
The melting temperature of the nanowire is
identified as the point at which the electron
diffraction pattern disappears and the nanowire
starts to be evaporated. Lower Tm is translated
into potentially much reduced thermal programming
energy of data storage device.
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Future Outlook for Inorganic Nanowires
Nanowire-based Ultra-high Density Data Storage
Nanowire-based Detector Sensory Systems
Nanowire-based Hybrid Energy Conversion/Storage Un
it
Nanowire-based Peripheral Optical Interconnect/ Tr
ansmitter
Nanowire-based Radiation-harden Central
Processing Unit
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Summary
Nanotechnology is an enabling technology that
will impact electronics, computing, data
storage, communications, materials and
manufacturing, health and medicine, energy,
transportation, environment, national
security Though commercial applications have
started to emerge, it is still early and long
way to go before realizing true potential. Lot
more work needed on - Novel synthesis
techniques - Characterization and understanding
of nanoscale properties - Large scale
production of materials - Application and
product development Opportunities and rewards
are great and hence, tremendous worldwide
interest Integration of this emerging field
into engineering and science curriculum is
important to prepare the future generation of
scientists and engineers