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Nanotechnology: Advantages and Applications. M. Meyyappan Center for Nanotechnology NASA Ames Research Center Moffett Field, CA 94035 email: Melting point - 1064  C. What is Nanotechnology?.

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Nanotechnology: Advantages

and Applications

M. Meyyappan

Center for Nanotechnology

NASA Ames Research Center

Moffett Field, CA 94035



Melting point - 1064 C

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

unique properties of nanoscale materials
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

nni program component areas pcas
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










Nanotechnology R & D

and Related




Various Nanomaterials and


• Nanocrystalline materials

• Nanoparticles

• Nanocapsules

• Nanoporous materials

• Nanofibers

• Nanowires

• Fullerenes

• Nanotubes

• Nanosprings

• Nanobelts

• Dendrimers

• Molecular electronics

• Quantum dots

• NEMS, Nanofluidics

• Nanophotonics, Nano-optics

• Nanomagnetics

• Nanofabrication

• Nanolithography

• Nanomanufacturing

• Nanomedicine

• Nano-bio


Impact of Nanotechnology

• Information Technology

- Computing, Memory and Data Storage

- Communication

• Materials and Manufacturing

• Health and Medicine

• Energy

• Environment

• Transportation

• National Security

• Space exploration

Nanotechnology is an

enabling technology


• 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


• Carbon Nanotubes

• Nanostructured Polymers

• Optical fiber performs through sol-gel

processing of nanoparticles

• Nanoparticles in imaging systems

• Nanostructured coatings

• Ceramic Nanoparticles for netshapes

Source: IWGN Report


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

• Composites (high strength, light weight)

• Catalysts

• Insulators


Nanoelectronics and Computing


Shared computing thousands of people sharing a mainframe computer


Personal computing


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.


“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


1938 1998

Technology engine:

Vacuum tube

Proposed improvement:

Solid state switch

Fundamental research:

Materials purity

Technology engine:


Proposed improvement:

Quantum state switch

Fundamental research:

Materials size/shape

• 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


• Defect tolerant architecture, TERAMAC computer

by HP architectural solution to the

problem of defects in future molecular electronics

- Stan Williams, HP


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


• Expanding ability to characterize genetic makeup will

revolutionize the specificity of diagnostics and therapeutics

- Nanodevices can make gene sequencing more efficient

• Effective 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


biosensor for

cancer diagnostics


• 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


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


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


- Waste remediation

• Filters and Membranes

- Removal of contaminants

from water

- Desalination

• Reducing auto emissions, NOx conversion

- Rational design of catalysts


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



• 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


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-rovers that drive,

hop, fly, and burrow

- Collection of microspacecraft

making a variety of measurements

Europa Submarine


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: Young’s 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).


CNT Properties

• The strongest and most flexible molecular material because of C-C covalent bonding and seamless hexagonal network architecture

• Strength to weight ratio ~500 times greater than Al, steel,

titanium; one order of magnitude improvement over


• 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’)


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


• CNT quantum wire interconnects

• Diodes and transistors for computing

• Data Storage

• Capacitors

• Field emitters for instrumentation

• Flat panel displays



• 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



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

(temperature, choice of

feedstock, H2 and other

diluents, choice of catalyst

and preparation)


• SWNTs: Methane, 900° C, 10 nm Al/1.0 nm Fe

• MWNTs: Ethylene, 750º C, 20 nm

Al/10 nm Fe

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).


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


• dc, rf, microwave, inductive

plasmas (with a biased substrate)

have been used in PECVD of

such nanostructures

Cassell et al., Nanotechnology, 15 (1), 2004


CNT in Microscopy

Atomic Force Microscopy is a powerful technique for imaging; also CD metrology, nanomanipulation, as platform for sensor work, nanolithography...

Conventional silicon and other tips wear out quickly.

CNT tip is robust, offers amazing resolution.

2 nm thick Au on Micaimaged with SWNT

Simulated Mars dust

Written using multiwall tube

Nguyen et al., Nanotechnology, 12, 363 (2001)


193 nm IBM Version 2 Resist

DUV Photoresist Patterns Generated by Interferometric Lithography

Nguyen et al.,

App. Phys. Lett.,

81 (5), 901 (2002).

MWNT Scanning Probe:

Profilometry in Semiconductor Manufacturing







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


300 mm

200 mm

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


Single-Walled Carbon Nanotubes

For Chemical Sensors


•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



• One-dimensional quantum


• Bandgap varies with wire diameter

• Single crystal with well-defined

surface structural properties

• Tunable electronic properties

by doping

• Truly bottom-up integration


V.S. Vavilov (1994)

Various Inorganic Nanowires


• 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


Vertically-Aligned Nanowires

for Device Fabrication

Germanium Nanowires

ZnO Nanowires

H.T. Ng et al., Science, Vol. 300, p. 2149 (2003).

P. Nguyen et al., Advanced Materials, Vol. 17, p. 549 (2005).


PCM layer

PCM nanowire

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


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.


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.


Future Outlook for Inorganic Nanowires


Ultra-high Density

Data Storage


Detector Sensory



Hybrid Energy




Peripheral Optical





Central Processing Unit



• 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