Introduction to Nanotechnology:What, Why and How

Mark Tuominen, UMass, November 17, 2007

bnl

manchester

Nanotech: What?

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 billionth of a meter= 1 x 10-9 m

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

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

Nanotech: Why?

10 GB2001

20 GB2002

40 GB2004

80 GB2006

160 GB2007

Example: Advancement of the iPod

Hard driveMagnetic data storage

Uses nanotechnology!

Magnetic Data StorageA computer hard drive stores your data magnetically

Disk

N S

direction of disk motion

“ Write”Head

0 0 1 0 1 0 0 1 1 0 _ _

“ Bits” ofinformation

NS

“ Read”Head

Signalcurrent

Scaling Down to the Nanoscale

Increases the amount of data stored on a fixed amount of “real estate” !

Now ~ 100 billion bits/in2, future target more than 1 trillion bits/in2

25 DVDs on a disk the size of a quarter, orall Library of Congress books on a 1 sq ft tile!

Why do we want to make things at the nanoscale?

• To make better and new 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, technology. (Quantum behavior and other effects.)

Nanotech: How?

• How to make nanostructures?• How to characterize and test them?

Making Nanostructures: Nanofabrication

• Top down versus bottom up methods

•Lithography•Deposition•Etching•Machining

•Chemical•Self-Assembly

Nanostructuresmacroscale (3D) object

widthdepth

height

nanofilm, or nanolayer (2D)

nanowire,nanorod, ornanocylinder (1D)

nanoparticle,nanodot,quantum dot (0D)

Nanofilms(making thin objects)

An Early Nanotechnologist?

Excerpt from Letter of Benjamin Franklin to William Brownrigg (Nov. 7, 1773)

...At length being at Clapham, where there is, on the Common, a large Pond ... I fetched out a Cruet of Oil, and dropt a little of it on the Water. I saw it spread itself with surprising Swiftness upon the Surface ... the Oil tho' not more than a Tea Spoonful ... which spread amazingly, and extended itself gradually till it reached the Lee Side, making all that Quarter of the Pond, perhaps half an Acre, as smooth as a Looking Glass....

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... 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)

A monolayer NANOFILM (single layer of molecules)

~1 nm thickLangmuir film

An example of a FILM

This is an example of SELF-ASSEMBLY

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

Nanofilm by Electroplating

VI

Cu2+ + 2e- –> Cu(0)

"reduction"

CuSO4 dissolved in water

Cu(0) –> Cu2+ + 2e-

"oxidation"

anodecathode

If using an inert Pt electrode:

2 H2O –> O2 + 4H+ + 4e-

WorkingElectrode(WE)

CounterElectrode(CE)

BREAK

Imaging NanostructuresAtomic Force Microscope (AFM)

.

"Optical Lever" for Profilometry

cantilever

laser

.

"Optical Lever" for Profilometry

cantilever

laser

Long light path and a short cantilever gives large amplification

Ato

mic

For

ce M

icro

scop

eA

tom

ic F

orce

Mic

rosc

ope

AFM Cantilever Chip AFM Instrument Head

Laser Beam Path Cantilever Deflection

Image of Nickel AtomsSTM

Lithography(controlling width and depth)

Lithography

MarkTuominen

MarkTuominen

MarkTuominen

(Using a stencil or mask)

Photolithography for Deposition

substrate

process recipe

spin on resist

resist

expose

mask (reticle)

develop

deposit

liftoffnarrow line

apply spin bake

spin coating

exposed unexposed

"scission"

Lithography

IBMCopperWiringOn aComputerChip

PatternedSeveral Times

Electron-Beam Lithography

Silicon crystal

Polymer film

Electron Beam

Nanoscopic Mask !

Self-Assembled Nanostructuresand

Lithography Based on Self-Assembly

Self Assembly

Diatoms

priweb.org

sinancanan.net

Gecko feet

Abalone

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

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)

Application examples:Nanoelectronics

Computer

Microprocessor"Heart of the computer"

Does the "thinking"

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

Hard Disk Drives - a home for bits

Hitachi

Improving Magnetic Data Storage Technology

• The UMass Amherst Center for Hierarchical Manufacturing is working to improve this technology

Granular Media

PerpendicularWrite Head

Soft Magnetic UnderLayer (SUL)

coil

Y. Sonobe, et al., JMMM (2006)

1 bit

• CHM Goal: Make "perfect" mediausing self-assembled nano-templates• Also, making new designs for storage

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nanoporous template

nanowires in a diblockcopolymer template

Electrodeposited Nanowires in aNanoporous Polymer Template (Mask)

1x1012 wires/in2

Benefit: Sun is an unlimited source of electronic energy.

Solar Cells

Konarka

Electric Solar CellsMade from single-crystal silicon wafers (conventionally)

cross-sectional view

n-type silicon

p-type silicon

+

-

Sunlight

Voltage “load”

+

-

Current

The load can be a lamp, an electric motor, a CD player, a toaster, etc

wires

Nanostructured Solar Cells

+

-

Sunlight

Voltage “load”

CurrentMore interface area - More power!

Nanotechnology R&D is interdisciplinary and impacts many applications

• 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

Thanks for visiting UMass and learning about nanotechnology!