Overview of Nanoscience and Overview of Nanoscience and NanotechnologyNanotechnology

OOğuz Gülserenğuz Gülseren

Al

Al2O3

Barrier Layer

Pores

×× 300300

×× 300300

A pictorial definition of NanoA pictorial definition of Nano

Aphid

× 100

Paramecium × 100

Tina (Weatherby) CarvalhoBio Images by:

× 100

Electronics, circa 1985Electronics, circa 1985

40 nanometers40 nanometers

× 1000

Electronics, circa 2010Electronics, circa 2010

Electronics, circa 1985Electronics, circa 1985

Electronics, circa 2010Electronics, circa 2010

Electronics, circa 2040Electronics, circa 2040

X 100

1 nm diameter 1 nm diameter molecular wires molecular wires

The Incredible The Incredible TininessTininess of of NanoNano

Billions of nanometers

A two meter tall male is two billion nanometers.

A millionnanometers

The pinhead sized patch of this thumb is a million

nanometers across.

Thousands ofnanometers

Biological cells have diameters in the range of thousands of nanometers.

NanometersTen shoulder-to-shoulder hydrogen atoms span 1

nanometer. DNA molecules are about 2.5

nanometers wide.

Less than ananometer

Individual atoms are up to a few tenths of a

nanometer in diameter.

A human hair is approximately 100,000 nm.

nano = dwarf (Greek) nano = dwarf (Greek)

NaCl-(001) island on a Cu(111) surface

protonatom

virus

radius of the earth

earth-sun

radius ofgalaxies

NanoNano the lengths scales ofnano physics....

- atoms- molecules- clusters- solids

meter

Ångstrom

.....are the lengths scales of life

- atoms- molecules- cells- organisms

Nano = 10Nano = 10--99

1 nm = 101 nm = 10--9 9 mm

1 m 10 Å: 1,000,000,000

The visionThe visionThe classic talk: “There's Plenty of The classic talk: “There's Plenty of Room at the Bottom” Room at the Bottom” Richard Feynman,Richard Feynman, December 29, 1959. The December 29, 1959. The annual meeting of the American Physical Society annual meeting of the American Physical Society at Caltechat Caltech

• “Why cannot we write the entire 24 volumes of the Encyclopedia Britannica on the head of a pin?”

• “Biology is not simply writing information; it is doing something about it. A biological system can be exceedingly small.”

• “I want to build a billion tiny factories, models of each other, which are manufacturing simultaneously, drilling holes, stamping parts, and so on.”

World’s First Tiniest MotorWorld’s First Tiniest Motor

Richard Feynman viewing the micromotor built by William McLellan (left) who won the challenge to build the first motor smaller than 1/64th of an inch (left). The motor photographed under an optical microscope (right).

Picture credit: Caltech Archives

Red Herring, May 2002

Commonality: Railroad, auto, computer, nanotechall are enabling technologies

1970 1975 1980 1985 1990 1995 2000 2005 2010103

104

105

106

107

108

109Transistors per chip

Year

80786PentiumPro

Pentium80486

8038680286

8086

80804004

?

micro nano

Moore‘s LawMoore‘s Law

1985 1990 1995 2000 2010 2015 202010-1

100

101

102

103

104Electrons per device

2005Year

(Transistors per chip)

(16M)(4M)

(256M)(1G)

(4G)(16G)

(64M)

micro nano

Vanishing electronsVanishing electrons

PastShared computing thousands of people sharing a mainframe computer

PresentPersonal computing

FutureUbiquitous computing thousands of computers sharing eachand everyone of us; computers embedded in walls, chairs, clothing,light switches, cars….; characterized by the connection of things inthe world with computation.

The incredible shrinking disk drive

1956 IBM Ramac 305 vs. 2000 IBM Microdrive5 MB 1 GB50 x 24” dia. disks 1 x 1” diskweighs “a ton” < 1 oz.$50,000 $500

Nanotechnology R&D Funding in the USANanotechnology R&D Funding in the USA

Fiscal yearFiscal year 20002000 2001 20022001 2002 20032003(all in million $)(all in million $)

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

National Science FoundationNational Science Foundation 9797 150150 199 199 221221Department of DefenseDepartment of Defense 7070 125125 180180 201201Department of EnergyDepartment of Energy 5858 8888 91.1 139.391.1 139.3National Institutes of Health National Institutes of Health 3232 39.639.6 40.840.8 43.2 43.2 NASANASA 55 2222 46 51 46 51 NISTNIST 88 33.433.4 37.6 43.8 37.6 43.8 Environmental Protection Agency Environmental Protection Agency -- 5.85.8 55 55Depart. of Transportation/FAA Depart. of Transportation/FAA -- 22 22Department of Agriculture Department of Agriculture -- 1.51.5 1.51.5 2.52.5Department of Justice Department of Justice -- 1.41.4 1.4 1.41.4 1.4TOTALTOTAL 270.0 270.0 466.7466.7 604.4 710.2 604.4 710.2

Other NNI participants are: DOC, DOS, DOTreas, NOAA, NRCOther NNI participants are: DOC, DOS, DOTreas, NOAA, NRC, USG, USG

M.C. Roco, NSF, 4/30/02

0

500

1000

1500

2000

2500

1997 1998 1999 2000 2001 2002

mill

ions

$ /

year

W. EuropeJapanUSAOthersTotal

Senate Briefing, May 24, 2001 (M.C. Roco), updated on February 5, 2002

• U.S. begins FY in October, six month before EU & Japan in March/April• U.S. does not have a commanding lead as it was for other S&T megatrends

(such as BIO, IT, space exploration, nuclear)

Context Context –– Nanotechnology in the WorldNanotechnology in the WorldGovernment investments 1997Government investments 1997--20022002

Note:

Nanostructures:Nanostructures:

a.a. Contain a Contain a countablecountable number of number of atomsatoms

b.b. Suites for Suites for atomic levelatomic level detailed detailed engineeringengineering

c.c. Provide access to realms of Provide access to realms of quantum behaviorquantum behaviorthat is not observed in larger (even 0.1 µm) that is not observed in larger (even 0.1 µm) structuresstructures

d.d. Combine Combine small sizesmall size, , complexcomplex organizational organizational patternspatterns, potential for very , potential for very high packinghigh packing densities, densities, strong lateral strong lateral interactionsinteractions and high ratios of and high ratios of surface area to volume.surface area to volume.

SoSo…….What are Nanoscience and Nanotechnology?.What are Nanoscience and Nanotechnology?

The ability to observe, The ability to observe, measure, predict and measure, predict and construct construct —— on the scale on the scale of atoms and moleculesof atoms and moleculesand and exploitexploit the novel the novel properties found at that properties found at that scale.scale.

……and beyond the nice definitions and beyond the nice definitions ……What it really isWhat it really is……..

• Examples- Carbon Nanotubes- Proteins, DNA- Single electron transistors

• Not just size reduction but phenomena intrinsic to nanoscale- Size confinement- Dominance of interfacial phenomena- Quantum mechanics

• New behavior at nanoscale is not necessarily predictable from what we know at macroscales.

AFM Image of DNA

Source: Nanoscale Materials in Chemistry, Wiley, 2001

The melting point decreases dramatically as the particle size gets below 5 nm

Source: Nanoscale Materials in Chemistry, Wiley, 2001

Nanostructures (< 30 nm) have become an exciting research Nanostructures (< 30 nm) have become an exciting research fieldfield–– New quantum phenomena occur at this length scaleNew quantum phenomena occur at this length scale–– New structure New structure –– property relations are expectedproperty relations are expected–– Promising applications are expected in optics, electronics, Promising applications are expected in optics, electronics,

thermoelectric, magnetic storage, NEMS (nanothermoelectric, magnetic storage, NEMS (nano--electroelectro--mechanical systems)mechanical systems)

LowLow--dimensional systems are realized by creating dimensional systems are realized by creating nanostructures that are quantum confined in one or more nanostructures that are quantum confined in one or more directions and directions and exhibit properties different from their 3D exhibit properties different from their 3D counterpartscounterparts

3DBulk Semiconductor

2DQuantum Well

1DQuantum Wire

0DQuantum Dot

E

D. O

. S.

D. O

. S.

D. O

. S.

D. O

. S.

E E E

• For semiconductors such as ZnO, CdS, and Si, the bandgapchanges with size

- Bandgap is the energy needed to promote an electron from the valence band to the conduction band

- When the bandgaps lie in the visible spectrum, changing bandgap with size means a change in color

• For magnetic materials such as Fe, Co, Ni, Fe3O4, etc., magnetic properties are size dependent

- The ‘coercive force’ (or magnetic memory) needed to reverse an internal magnetic field within the particle is size dependent

- The strength of a particle’s internal magnetic field can be size dependent

Motivation towards NanotechnologyMotivation towards Nanotechnology

Nanometer scale physics and chemistry might Nanometer scale physics and chemistry might lead directly to:lead directly to:

Smaller and faster electronic devices.Smaller and faster electronic devices.Device miniaturization by reducing their physical sizesDevice miniaturization by reducing their physical sizesExploiting enhanced surface effects by increased surface/volume Exploiting enhanced surface effects by increased surface/volume ratio (e.g. catalysts)ratio (e.g. catalysts)Stronger and lighter materials with more functionality.Stronger and lighter materials with more functionality.Utilization of biological objects in inorganic nanostructures foUtilization of biological objects in inorganic nanostructures for r various sensors and novel functionsvarious sensors and novel functionsSupply instrumentation to speed gene sequencing and chemical Supply instrumentation to speed gene sequencing and chemical agents to detect tumors.agents to detect tumors.Store Library of Congress on a device the size of a sugar cube.Store Library of Congress on a device the size of a sugar cube.Exciting new science discoveries because the properties of nanoExciting new science discoveries because the properties of nano--materials are expected to be different from their bulk counterpamaterials are expected to be different from their bulk counterparts.rts.Novel phenomena in lowNovel phenomena in low--dimensional structuresdimensional structuresDirect observation of physics laws in nanostructuresDirect observation of physics laws in nanostructures

““NanoNano” Timeline” Timeline19051905: Einstein published a paper that estimated the : Einstein published a paper that estimated the diameter of a sugar molecule as 1 nm.diameter of a sugar molecule as 1 nm.19591959: Richard Feynman’s famed talk.: Richard Feynman’s famed talk.19811981: : BinnigBinnig and Rohrer created the STM to image and Rohrer created the STM to image individual atoms.individual atoms.19851985: Curl, : Curl, KrotoKroto, Smalley discovered C, Smalley discovered C6060..19931993: : IijimaIijima, Bethune discovered single wall carbon , Bethune discovered single wall carbon nanotubes.nanotubes.19981998: : CeesCees Dekker’sDekker’s group created a TUBEFET.group created a TUBEFET.20012001: Nanowire : Nanowire ZnOZnO laserlaser20022002: : SuperlatticeSuperlattice NanowiresNanowires

(Schmidt et. al.)

ClustersClusters

(a) Bi Nanowire (b) Bi Nanotube (c) Bi Atomic Line

Various Nanostructures can occur in 1DEach have different structure/properties

Selectivity is therefore important

K. MikiETL,Japan

Peidong YangUC Berkeley

Dresselhaus Group(MIT)

TEM of CdSe quantum rods, with average size 25*4 nm.

(Banin et. al.)

NanoparticlesNanoparticles

TEM of CdSe quantum rods, with average size 25*4 nm.

Membrane ProteinsMembrane Proteins

Examples of Quantum WiresExamples of Quantum Wires

Nanotube

(Dekker et. al.)The Fullerenes:Nanoscale control

over materials properties

Nobel Prize in Chemistry, 1996

Nanotubes

DNA

(Cohen et. al.)

3.4 Å

34 Å

Example of DNAExample of DNA--Nanotube hybridNanotube hybrid

(Dekker et. al.)

A scanning tunneling microscope image of a Single-Walled Carbon NanotubeA symbol of the origins of Nanoscience & Nanotechnology

Unique Properties of Carbon Unique Properties of Carbon NanotubesNanotubes

• Size: Nanostructures with dimensions of ~1 nm diameter (~20 atoms around the cylinder)

• Electronic Properties: Can be either metallic or semiconducting depending on the diameter or orientation of the hexagons

• Mechanical: Very high strength and modulus. Good properties on compression and extension

• Heat pipe and electromagnetic pipe• Single nanotube spectroscopy yields structure• Many applications are being attempted worldwide

Graphene sheet SWNT

Roll up

2 2

1 21

( , )3tan

2

t

h

L ad n nm mC na ma n m

mn m

π π

θ −

= = + += + ≡ = +

(4,2)

Rolling up graphene layer

0θ = °

0 30θ< < °

30θ = °armchair

zigzag

chiral

Nanotubes

(n-m) = 3q metallic(n-m) = 3q ±1 semiconducting

The Fullerenes:Nanoscale control over materials propertiesNobel Prize in Chemistry, 1996

The Scanning Tunneling Microscope: Resolving the atomic worldNobel Prize in Physics, 1988

The Development of Technological Means The Development of Technological Means and Computational Power Sufficient for and Computational Power Sufficient for Visualizing and operating in the NanoVisualizing and operating in the Nano--WorldWorld

Main Tools for Nano:Main Tools for Nano:

1.1. ObservationObservation::a)a) SEM/TEM (optical)SEM/TEM (optical)b)b) SPMSPM

2.2. ConstructionConstruction::a)a) EE--beam/optical Lithographybeam/optical Lithographyb)b) SPM LithographySPM Lithographyc)c) Self assemblySelf assemblyd)d) ChemistryChemistry

There are two ways to build a house…...

TopTop--downdown

BottomBottom--upup

A “Nano ToolA “Nano Tool--box”box”

To fabricate/probe nanostructuresTo fabricate/probe nanostructures

NanofabricationNanofabrication

Top-down Method

- create nanostructures out of macrostructures

Bottom-up Method

- self assembly of atoms or molecules into nanostructures

Scanning Tunneling Microscope (STM)Scanning Tunneling Microscope (STM)

Sample

Piezo

Electronics(Current+Feedback)

Computer(Control)

Matrix ofheights(Image)

Tip

I(V) ~ Ve-(ks)

Tunneling between a sharp tip and conducting surface.Piezo enables xy and z movement.Working mode: constant current.The feedback voltage Vz(x,y) is translated to height (topographic) information.

STM ImagesSTM Images

Graphite – atomic resolution: Supercoiled DNA

Atomic Force Microscope ( AFM) PrincipleAtomic Force Microscope ( AFM) Principle

AFM ImagesAFM Images

Magnetic bits of a zip disk G4-DNA

100nm10µm

DNA-NanotubeNanotube between

electrodes

AFM nanographyAFM nanographyatomic force microscope

manipulate a surfaceby- applying a local electric field

- local oxidation

(Avouris et al. IBM)

Carbon Nanotube Manipulation

AFM Scanning

Lowering the tip and pushing

VDW forces hold the CNT

……For exampleFor example……..

(Eigler et. al.)

Directions of development in Nano:Directions of development in Nano:

1.1. NanoelectronicsNanoelectronics2.2. NanoNano--mechanics mechanics

(MEMS/NEMS)(MEMS/NEMS)3.3. NanoNano--bio(techno)logybio(techno)logy4.4. NanoNano--medicinemedicine

Nanotube circuits Nanotube circuits ((CeesCees Science cover)Science cover)

(Avouris et al. IBM)

A Field-Effect Transistor Made from a Single-Wall Carbon Nanotube

(Avouris et al. IBM)AFM Oxidation

61 % Humidity 14 % Humidity

Applications for NanotubesApplications for NanotubesScanning tips and Scanning tips and

ElectronicsElectronicsSTM/AFM tipsSTM/AFM tipsDirect Analysis of DNADirect Analysis of DNASemiconductor devicesSemiconductor devicesField EmittersField Emitters

S.J. Tans et al. Nature, 393, 49 (1998)

AFM image of Immunoglobulin G resolved by nanotube tips

Field Emitter

Transistor

Imaging biological molecules

New Materials

Fullerene C60 inside nanotubes

Potential for high hydrogen Potential for high hydrogen capacity capacity relativerelative to other to other carbon structures.carbon structures.–– single wall structuresingle wall structure–– multiple adsorption sitesmultiple adsorption sites–– high packing density if alignedhigh packing density if aligned–– 8 wt% for pure materials at 80K 8 wt% for pure materials at 80K

(Caltech/JPL)(Caltech/JPL)–– 7 wt% at room temperature (NREL)7 wt% at room temperature (NREL)

Issues:Issues:–– wide variability in resultswide variability in results–– processing uncertaintiesprocessing uncertainties–– synthesis of large quantities with synthesis of large quantities with

high purity at low costhigh purity at low cost–– Small amount of energy required for Small amount of energy required for

adsorption and adsorption and desorptiondesorption

B. Pradhan, et al 2001

L. Schlapbach, A. Zuttel 2001

Carbon Nanotubes for Hydrogen storageCarbon Nanotubes for Hydrogen storage

Reproducibility is a key issue for carbon nanotubes.

Organic Nanostructures: The Electrical Organic Nanostructures: The Electrical Conductivity of a Single Molecule (breakConductivity of a Single Molecule (break--junctions)junctions)

(Reed et al. 1997)

Resonant Tunneling Devices in Nanoelectronics

4 bit 2 GHz analog-to-digital converter, 3 GHz (40 dB spur-free dynamic range) clocked quantizer, 3 GHz sample and hold (55 dB linearity), clock circuits, shift registers, and ultralow power SRAM (50 nW/bit)

(Seabaugh 1998)

(Avouris et al. IBM)Theory of CNTTwisting angle

effect on energy band-gap

Bending effect of on CNT Electronic Structure

(A) Streptavidin molecules bind to a silicon nanowire functionalized with biotin.The binding of streptavidin to biotin causes the nanowire to change its resistance. (B)The conductance of a biotin-modified silicon nanowire exposed to streptavidinin a buffer solution (regions 1 and 3) and with the introduction of a solution of antibiotin monoclonal antibody : (region 2) (Cui et al., 2001).

Si Nanowire Sensor

biotin

*Direct read-out of binding of antigen-antibody.

*Multiple sensors can be used for laboratory test

Quantum Confinement Produces New Quantum Confinement Produces New Materials ClassesMaterials Classes

• Bi – Group V element– Semimetal in bulk form– The conduction band (L-electron)

overlaps with the valence band (T-hole) by 38 meV

Decreasing wire diameter

Semimetal Semiconductor

• Bi nanowire– Semimetal-semiconductor

transition at a wire diameter about 50 nm due to quantum confinement effects

SemimetalSemimetal--Semiconductor TransitionSemiconductor TransitionWe utilize novel properties in applications

Tunable Tunable BandgapBandgap in Nanowiresin Nanowires

InP nanowire

diameter ↓

energy ↑

M. S. Gudiksen et al., J. Phys. Chem B 106, 4036 (2002)

With same material luminescence devices with different emission frequencies can be made

NanoNano--Lasers using Lasers using ZnOZnONanowiresNanowires

ZnO nanowires grown by VLS method.

Emission spectrum from ZnO nanowires.Peidong Yang et al

Wavelength (nm)370 380 390 400

Inte

nsity

(a.u

.)

Nanowire UV Nanolaser

UV Laser Output

Excitation

SuperlatticeSuperlattice Nanowires for Nanowires for

Thermoelectric ApplicationsThermoelectric Applications

Superlattice (2D) Nanowire (1D)

Superlattice Nanowire (0D)

phonon

e- Electron transmitting

Phonon blocking

Y.-M. Lin in Dresselhaus MITgroup

Published in Nature

• Quantum Computing- Takes advantage of quantum

mechanics instead of being limited by it

- Digital bit stores info. in the form of ‘0’ and ‘1’; qubitmay be in a superposition state of

‘0’ and ‘1’ representing both valuessimultaneously 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 transistor by IBM and Delft University

• Molecular electronics: Fabrication of logic gatesfrom molecular switches using rotaxanemolecules

• Defect tolerant architecture, TERAMAC computerby HP architectural solution to theproblem of defects in future molecular electronics

• Expanding ability to characterize genetic makeup willrevolutionize 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

Nanotube-basedbiosensor forcancer diagnostics

Optoelectrical characterization of a crossed nanowire junction formed between65-nm n-type and 68-nm p-type InP nanowires. (a) Electroluminescence (EL) image of thelight emitted from a forward-biased nanowire p-n junction at 2.5 V. Inset, photoluminescence(PL) image of the junction. (b) EL intensity as a function of operation voltage. Inset, theSEM image and the I-V characteristics of the junction (Duan et al., 2001). The scale bar inthe inset is 5 microns.

I-VPLEL

Luminescence from Nanowire Junctions

*Light emission from nanowire junctions

SelfSelf--Assembled Assembled NanoporesNanopores in Aluminain Aluminafor growing nanowires/nanotubesfor growing nanowires/nanotubes

ApplicationsApplications–– Templates for ordered Templates for ordered

arrays of nanowires and arrays of nanowires and nanotubesnanotubes

–– 2D photonic crystal2D photonic crystal–– High density magnetic High density magnetic

storage mediastorage media

Al

Al2O3

Barrier Layer

Pores

Free-standing wires

Nanowire array

SEM image of the surface of an anodic alumina template with self-assembled nanopore structure

Template Dissolution

Nanowire Array (Charles Nanowire Array (Charles LieberLieber))

Addressable array for logic functions

A Commercial IBM Giant MagnetoresistanceRead Head

‘Self-healing plastic’ by Prof. Scott White (U. of Illinois) Feb. 15, 2001, Issue of Nature

• Plastic components break because of mechanical or thermalfatigue. Small cracks large cracks catastrophic failure.‘Self-healing’ is a way of repairing these cracks without humanintervention.

• Self-healing plastics have small capsules that release a healingagent when a crack forms. The agent travels to the crack through capillaries similar to blood flow to a wound.

• Polymerization is initiated when the agent comes into contactwith a catalyst embedded in the plastic. The chemical reactionforms a polymer to repair the broken edges of the plastic. New bond is complete in an hour at room temperature.

Quantum Information ScienceQuantum Information Science Nanoscale MaterialsNanoscale Materials

Biology & HealthcareBiology & Healthcare

Molecular ElectronicsMolecular Electronics

BIG future for NANO

• If nano research is the Mt. Everest, we have barely reached the base camp!(Charles Lieber)

• If Einstein were looking for a career path today, his advisor would tell him to think small: “Nanotech, Albert, nanotech” (Gary Stix)