Introduction to NanotechnologyJuly 23, 2007

bnl

manchester

Some things we will discuss:

• How big are nanostructuresScaling down to the nanoscale

• How are nanostructures made?Fabrication, synthesis, manufacturing

• How do we see them?Imaging and property characterization (measurement)

• Why do we care?Applications to science, technology and society

Introduction to NanotechnologyJuly 23, 2007

Why do we want to make things at the nanoscale?

• To make better products: smaller, cheaper, faster and more effective. (Electronics, catalysts, water purification, solar cells, coatings, medical diagnostics & therapy, etc)

• To introduce completely new physical phenomena to science and technology. (Quantum behavior and other effects.)

Nanotechnology

Nanotechnology is the understanding and control of matter at dimensions of roughly 1 to 100 nanometers, where unique phenomena enable novel applications.

1 nanometer = 1 x 10-9 m= 1 billionth of a meter

nano.gov

How small are nanostructures?

Single Hair

Width = 0.1 mm

= 100 micrometers

= 100,000 nanometers !

1 nanometer = one billionth (10-9) meter

Smaller still

Hair

.

Red blood cell

6,000 nanometersDNA

3 nanometers

Down to the Nanoscale

From DOE

A Few Nanostructures Made at UMass100 nm dots 70 nm nanowires 200 nm rings

12 nm pores 14 nm dots

13 nm rings 25 nm honeycomb14 nm nanowires

18 nm pores

150 nm holes

"Nano"

• Nanoscale - at the 1-100 nm scale, roughly• Nanostructure - an object that has nanoscale

features• Nanoscience - the behavior and properties of

nanostructures• Nanotechnology - the techniques for making and

characterizing nanostructures and putting them to use

• Nanomanufacturing - methods for producing nanostructures in reliable and commercially viable ways

Nanotechnology R&D is interdisciplinary and impacts many industries

• Physics• Chemistry• Biology• Materials Science• Polymer Science• Electrical Engineering• Chemical Engineering• Mechanical Engineering• Medicine• And others

• Electronics• Materials• Health/Biotech• Chemical• Environmental• Energy• Aerospace• Automotive• Security• Forest products• And others

An application example:Nanoelectronics

Making Small SmallerAn Example: Electronics-Microprocessors

ibm.commacroscale

microscale

nanoscale

Electronics Keep On Getting BetterMoore's "Law": Number of Transistors per Microprocessor Chip

intel.com

Since the 1980's electronics has been a leading commercial driver for nanotechnology R&D, but other areas (materials, biotech, energy, etc) are of significant and growing importance.

Some have been around for a very long time:• Stained glass windows (Venice, Italy) - gold nanoparticles• Photographic film - silver nanoparticles• Tires - carbon black nanoparticles• Catalytic converters - nanoscale coatings of platinum and palladium

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

"Biggest science initiative since the Apollo program"

nano.gov

National Nanotechnology InitiativeResearch Areas (2007 Federal Budget)

1.Fundamental Nanoscale Phenomena and Processes2.Nanomaterials3.Nanoscale Devices and Systems4.Instrumentation Research, Metrology and Standards for Nanotechnology5.Nanomanufacturing6.Major Research Facilities and Instrumentation Acquisition7.Societal Dimensions

nanomanufacturing.org

A National Science Foundation Nano Center

Nanostructures

Nanostructuresmacroscale (3D) object

widthdepth

height

nanofilm, or nanolayer (2D)

nanowire,nanorod, ornanocylinder (1D)

nanoparticle,nanodot,quantum dot (0D)

Making Nanostructures: Nanofabrication

• Top down versus bottom up methods

•Lithography•Deposition•Etching•Machining

•Chemical•Self-Assembly

Nanofilms(making an object thin)

A monolayer NANOFILM (single layer of molecules)

~1 nm thickLangmuir film

An example of a FILM

This is an example of SELF-ASSEMBLY

... the Oil tho' not more than a Tea Spoonful ...

... perhaps half an Acre

CHALLENGE: How thick was the film of oil?

Volume = (Area)(Thickness)

V = A t

V = 1 teaspoonful

A = 0.5 acre

~ 2 cm3

~ 2,000 m2

t = V/A

20,000,000 cm2

= 2 cm3

20,000,000 cm2

= 0.0000001 cm = 1 x 10-7 cm= 1 x 10-9 m= 1 nanometer (nm)

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

LangmuirFilm pressure

e.g., oleic acid

monolayer filmwater

hydrophilic end

hydrophobic end

of an amphiphilicmolecule

Langmuir-Blodgett FilmMust control movablebarrier to keep constantpressure

multiple dips -multiple layers

Another film method,Thermal Evaporation

Vaporization or sublimation of a heated material onto a substrate in a vacuum chamber

vacuum~10-7 torr

sample

source

film

vacuumpump

QCM

vapor

resistive, e-beam, rf or laserheat source

Pressure must be held low to prevent contamination!

Au, Cr, Al, Ag, Cu, SiO, others

There are many otherthin film manufacturingtechniques

Lithography(controlling width and depth)

Lithography

MarkTuominenMark

TuominenMark

Tuominen

(Using a stencil or mask)

Making a nanoscopic mask

Silicon crystal

Polymer film

Electron Beam

Nanoscopic Mask !

Example: Electron-Beam Lithography

Lithography

IBMCopperWiringOn aComputerChip

PatternedSeveral Times

Self-Assembled Nanostructures

Self

Assembly

Tobacco Mosaic Virus

wisc.edu

nih.gov

Gecko feet

Diatoms

priweb.org

sinancanan.net

Abalone

The Cell and Its Hierarchy

ebi.ac.uk

Whitesides et al. Science 295, 2418 (2002);

Self assembly at all scales?

NANOFABRICATION BY SELF ASSEMBLY

Block “A” Block “B”

10% A 30% A 50% A 70% A 90% A

~10 nm

Ordered Phases

PMMA PS

Scale set by molecular size

One Example: Diblock Copolymers

CORE CONCEPT FOR NANOFABRICATION Deposition

Template

EtchingMask

NanoporousMembrane

Remove polymerblock within cylinders(expose and develop)

Versatile, self-assembling, nanoscale lithographic system

(physical orelectrochemical)

NANOFABRICATIONUSING DIBLOCK COPOLYMER TEMPLATES

template dots

rings holescylinders

Measuring Nanostructures

How do we see nanostructures?

• A light microscope? Helpful, but cannot resolve below 1000 nm

• An electron microscope? Has a long history of usefulness at the nanoscale

• A scanning probe microscope? A newer tool that has advanced imaging

Television Set

eye

electron beam

TV screen

Light !electronsource

prelim.

Scanning Electron Microscope

SAMPLE

ElectronBeam

DETECTOR

(Atomic Force Microscope) "Optical Lever"

To determine amplification factor, use the concept of similar triangles

laser pointer

Scanning probe microscope

Surface

Vibrating Cantilever

PS/PEO

AFM image

µm(large )

Laser Beam

AFM, STM, MFM, others

Qui

cktim

eQ

uick

time

AFM Cantilever Chip AFM Instrument Head

Laser Beam Path Cantilever Deflection

Scanning probe microscope

Surface

Vibrating Cantilever

PS/PEO

AFM image

µm(large )

Laser Beam

AFM, STM, MFM, others

Image of Nickel AtomsSTM

Pushing Atoms Around

STM

"Optical Lever"

y1

x1

y2

x2

€

y2x2=y1x1

€

y2 =x2x1y1

For example, if the laser pointer is 2" long, and the wall is 17' (204") away,

€

y2 =204

2y1 ≈100y1 Motion amplified

by 100 times!

.

"Optical Lever" for Profilometry

cantilever

laser

.

"Optical Lever" for Profilometry

cantilever

laser

Long light path and a short cantilever gives large amplification