Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf ·...

67
Designing Nanoscale Materials Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research Ornstein Laboratory 166 Office phone 253 2227 [email protected]

Transcript of Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf ·...

Page 1: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Designing Nanoscale MaterialsLecture Series by 2004 Debye Institute Professor

Christopher B. MurrayIBM Research

Ornstein Laboratory 166Office phone 253 2227

[email protected]

Page 2: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Lecture Series: Designing Nanoscale Materials.

(1) Why smaller, is different; finite size effects & implications for Tech scaling.

(2) General nanoparticle production.

(3) Semiconductor nanocrystals (Quantum Dots)Part 1:

(4) Semiconductor nanocrystals (Quantum Dots), Part 2:

(5) Nanowires

(6) Nanostructured magnetic materials for IT

(7) Nanomagnetics for biotech & beyond.

(8) Self-assembled nanocrystal superlattices:

(9) Binary nanocrystal assembly a route to multifunctional nanomaterials.

(10) Nanoporous materials:

(11) Ethics, issues and emerging trends for nanomaterials research.

Page 3: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Designing Nanoscale Materials

1+2 Wed. Sept 08 10.00-12.303+4 Wed. Sept. 15 10.00-12.30 5 Mon. Sept. 20 11.00-12.306+7 Wed. Sept. 29 10.00-12.30 8+9 Wed. Oct. 06 10.00-12.30 10+11 Wed. Oct. 13 10.00-12.30

Page 4: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Why smaller, really is different:Finite size effects in nanomaterials their implications for scaling in conventional technology.

Christopher B. MurrayManager Nanoscale Materials & DevicesIBM Research

Page 5: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Balancing the investments in Nanotechnology:

Basic/Strategic Research

Extending theEstablished

Technologies

Exploring Alternative/Disruptive

Technologies

ImmediateImpact

Long-TermImpact

Page 6: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Three Questions

What is nanotechnology?

Why is nanotechnology the future of information technology?

How will we manufacture at the nanoscale?

Page 7: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Nanotechnology is …

… research and technology development at the atomic, molecular or macromolecular levels, in the

length scale of approximately 1 – 100 nm …

National Science Foundation

Page 8: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

A Unique Period in History

after C. Ausschnitt, Microelectronic Engineering, 41/42 (1998) 41- 460.0001

0.001

0.01

0.1

1

10

100

1000

1800 1850 1900 1950 2000 2050 2100

Min

imum

mac

hine

d di

men

sion

(micr

ons)

Moore’s Law (1965)

90 nm Manufacturing (2004)

193 nm immersion

2004 commercial niche lithographies

2004 best lab practice

industry roadmapEUV

Page 9: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

C om puting : W here D o W e G o From H ere?

i10 mi100 nm

N anoscale S cience

and Techn o logy

Page 10: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Decreasing Costs of Computation

Source: Kurzweil 1999 – Moravec 1998

Page 11: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Constant Field Scaling

RESULTS:Higher Density: α2

Higher Speed: αLower Power: 1/α2

per circuit Power Density: Constant

L xd

GATEn+ source

n+ drain

WIRINGVoltage, V

W

p substrate, doping NA

tox

SILICON WAFER

L/α xd/α

GATEn+

sourcen+ drain

WIRING

Voltage, V / α

W/α

p substrate, doping α*NA

tox /α

SILICON WAFER

Page 12: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Silicon Transistor - Already A NanodeviceLogic

TSi=7nm Lgate=6nm

Source Drain

Gate

• Power4 Chip

• 174 million transistors• Gate length = 6 nm

B. Doris et al., IEDM , paper 10.6, 2002. J. Warnock et al., IBM J. R&D, p. 27, 2002

Page 13: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Size dependent phase transformationThe transition from c49 to c54 TiSi2Result in a

Phases formed by heating of a 10nm Ti film. As-deposited, the grain size is ~10nm (annealing at low Temp small would yield TiSi. The TiSi2 C49 phase appears at 700°C while C54 forms at 850°C.

Page 14: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Silicon Transistor - Already A NanodeviceMemory

• 512Mb DRAM prototype for 1Gb and beyond

• 110 nm DRAM, 8F2

S. Wuensche et al., Symp. VLSI Technology, 2002 H. Akatsu et al., Symp. VLSI Technology, p. 52, 2002

Page 15: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

The conventional silicon field-effect transistor is still rapidly advancing, with potential materials innovations such as …

channel

insulator

silicon substrate

insulator

Gate

Source Drain

Metal gate electrodes

High-dielectric constant gate insulators

Ultra-thin (2 – 20 nm)Si or Ge on insulator

High-electron-mobilitysubstrates (strain or orientation)

Page 16: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Si epitaxy on oxideEpitaxial Growth of Semiconductors on Crystalline Oxides

x-ray reflectivity

0.00 0.01 0.02 0.0310-6

10-5

10-4

10-3

10-2

10-1

100

qz (nm-1)

refle

ctiv

ity

simulation........ experiment

Ge epitaxy on oxide

Bojarczuk, Guha et al., Appl. Phys. Lett. V83, 5443-5, (2003)

Page 17: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Double-gate Transistor (FinFET)

Poly-Si

Tsi=20nm Tox=1.6nm H=65nm

BOX

TEOS

H

Tsi

TEM

Tox

current-carrying surfaces

Cross-section of 60 nm channel length FET

• Scalable to the smallest channel length• World-record double-gate FET device performance

“gate delay” = 0.92 ps

Page 18: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

single-electron charging energy

r r2d C ~ 2πε0εr[ln(r/d)] d<<r

~ 1.3 aF

2-d hcp lattice, each nanocrystal has 6 nearest neighbors (nn):

Cnn = 7.8 aF

to charge nanocrystal with a single extra electron:

Ec = ~ 10 meV e2

2Cnn

Coulomb energy dominates below ~ kBT=Ec/2

T~ 60Ko

Chuck Black, Bob Sandstrom, Chris Murray, Shouheng Sun

Coulomb Blockade Effects:

Page 19: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Electronic Properties of Semiconductor and Metal Nanoparticles

ε

a

Charge not completely solvatedas in infinite solid

aC oεπε4=Nanoparticle capacitance

)(2

2

aCeEc =Charging Energy

10 nm Al NC

Courtesy of C. T. Black, Thesis, Harvard U.

Coulomb blockade atkBT<Ec

Structure from discrete electronic states of metal NC

Page 20: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

STM Measurements on Single QDs

InAs QDs

U. Banin et al. Nature 400, 542 (1999).

Page 21: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Parameters in NC arrays

Transport – explained from Middleton-Wingreen(M-W) model

transport in linear and square arrays (how ideal?)

Achieving high operational T.Fabrication method affects

– Size of particles

– Monodispersity

– Number of particles responsible for transport

– Dimensionality

– Homogeneity of array

Page 22: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Self assembly:single layer 2-D array of Au crystals

NC size : 2.2 - 2.9 nm, Interparticle distance s1-2=0.85nm, 1.2 0.1nm.(Threshold voltage)VT ~ 10VT independence! (12, 48, 77K)

e2/Cmax>kbT Global structural disorder (topology)Local structural disorder (voids,interparticle distance)Local charge disorder (e.g substrate,..)

R. Parthasarathy et al., Phys. Rev. Lett.87, 186807

Page 23: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

shortest current path ~ 8 nanocrystals

Chuck Black, Bob Sandstrom, Chris Murray, Shouheng Sun

-400

-200

0

200

400

I (pA

)

-0.4 -0.2 0.0 0.2 0.4V (V)

T = 70 KT = 2 K

GV=0 follows simple thermal-activation

10-3

10-2

10-1

100

101

102

GV

=0

(1/GΩ

)

80x10-3

604020

1/T (K-1

)

data fit by: ln(GV=0) = const. - Ec/kBTfrom fit to data, measure EC~ 10 meV

for all devices measured, 10 meV < EC < 14 meV

1.00

0.98

0.96

0.94

0.92

R/R

H=

0

-0.4 -0.2 0.0 0.2 0.4

applied field (T)

HH

Spin-dependent tunneling in Nanocrystal arrays

Page 24: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Phase separation of block copolymersto form columnar

arrays

Directed Self-assemblyExperimental Silicon Memory Device

The process is then used in fabricating

an exploratory silicon memory

deviceSource: C. Black, K. Guarini, IBM

Page 25: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Goal: Incorporate Nanoscale Components in IT Systems

Porous Dielectric for On-Chip Wiring

Poromer (dendritic polymer)

Page 26: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Ultra Low K Dielectrics

Page 27: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Basic Physics of Semiconductor Quantum DotsC. R. Kagan, IBM T. J. Watson Research Center, Yorktown Heights, NY

HighestOccupiedMolecularOrbital

LowestUnoccupiedMolecularOrbital

ConductionBand

ValenceBand

EnergyGap

Bulk Semiconductor Quantum DotLike a

Molecule

Page 28: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Quantum ConfinementLow Dimensional Structures

( )( )n

c EEE

−∝

1ρ( ) tconsEc tan=ρ ( ) ( )nc EEE −∝ δρ( ) ( )Cc EEE −∝ρ

Page 29: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Particle-in-a-Sphere

is a spherical harmonic( )φθ ,mlY

( ) ( ) ( )rYrkj

Crm

llnl φθφθ

,,, ,=Φ

is the lth order spherical Bessel function( )rkj lnl ,

ak ln

ln,

=

2

2,

22,

2

, 22 ammk

Eo

ln

o

lnln

α==

a

0

Pot

entia

l V

r

1s

2s

solutions givehydrogen-like orbitals with

quantum numbersn (1, 2, 3 …)l (s, p, d …)

m

Discrete energy levels

size-dependence

Page 30: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Size Dependent AbsorptionExample: CdSe

Energy (eV)1.5 2.0 2.5 3.0 3.5

Abs

orba

nce

(arb

itrar

y un

its)

Energy (eV)1.5 2.0 2.5 3.0 3.5

Absorbance (arbitrary units)

17Å

150Å

17 Å

21 Å

29 Å

33 Å

45 Å

55 Å

72 Å

90 Å

150 Å

Page 31: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Real Band Structure

Example: CdSe

E

Eg

k

Cd 5s orbitals2-fold degenerate at k=0

Se 4p orbitals6-fold degenerate at k=0Introduces splitting of bands

hh

lh

so

heavy hole

light hole

spin-orbit splitoff J=1/2

J=3/2∆so

∆cfcrystal field splitting

J=1/2

J = L + S where L=orbital angular momentumS=spin angular momentum

J good quantum number due to strong spin-orbit coupling

Page 32: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Metal Nanoparticles

MetalParticle-- -

-------

- ---

-------- -

Surface Plasmon Resonance

• dipolar, collective excitation between negatively charge free electrons and positively charged core

• energy depends on free electron density and dielectric surroundings

• resonance sharpens with increasing particle size as scattering distance to surface increases

Au nanoparticle absorption

Page 33: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research
Page 34: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research
Page 35: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Antiferromagnetically-Coupled media

Three-atom-thick layer of Ru sandwiched between two magnetic layersExpected to increase current areal density limits to surpass 100 gigabits/inch2

Magnetic thickness = Mr t Magnetic thickness

= (Mr t)top - (Mr t)bottom

Page 36: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

AFC ( cont. )AFC Media

Page 37: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research
Page 38: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research
Page 39: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

MRAM Technology

Schematic of two MRAM cells

MRAM cell cross-sectionin 0.18 µm technology

Magnetic tunnel junction device and electrical characteristic

Mag

neto

resi

stan

ce (%

)

Applied Field (Oe)

M2

MT

M1

MTJBit

Line

Write Word Line

MT

128kb test chip

MRAM potentially has attributes of a universal memory: fast, dense, nonvolatile, radiation hard

Page 40: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

CatalysisAu nanoparticles supported on TiO2 substrates show high activity for oxidation of CO at room temperature and below.

Reaction proceeds at corner, step, and edge sites of Au

TiO2 Support

Oxygen Adsorption (on TiO2)

CO adsorption (on Au) 3.5 nm Au nanoparticle

12 Atoms in length

2-3 Atoms high

Haruta, M.; Date, M. Applied Catalysis A: General 2001, 222, 427-437.

Page 41: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Bimetallic Catalysis

CH2=CH-CN + H2O CH2=CH-CONH2

Reaction proceeds most favorably with Pd-Cu particles, and is 100% selective when using a 3:1 Cu:Pd ratio.

CH3-CH-CN

OH

Geometric effects lead to higher activity and selectivity for certain reactions.

Figure taken from: Toshima, N.; Yonezawa, T. New Journal of Chemistry 1998, 1179-1201 and references therein.

Page 42: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research
Page 43: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Two visions of nanofabrication…

“Old”

Top down

Lithography

Digital

Depend on Low Error Rates

Molecular Assemblers

“New”

Bottom up

Chemical Synthesis

Analog

Tolerate High Error Rates

Self-Assembly

Page 44: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Allowing a few components to approach equilibrium will produce only simple structures …

Synthesis

Reagents

Page 45: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

“Guiding” or “directing” the assembly process:Semiconductor Nanocrystals

Size ProcessingSynthesis Film Growth:Self-Assembly

Nanocrystal Superlattice

Reagents

Page 46: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Multi-Component Nanocrystal Superlattices

F. X. Redl, K. S. Cho and C. B. Murray

Page 47: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Silicon Nanowires: In-situ Observation of Growth

112

110111

dark-fieldimage

112

Si2H6

heated substrate

110

111

viewing direction

Frances Ross, IBM Research

Page 48: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Si nanowire growth

showing wire and drop geometry, facet formation and tapering to termination

Frances Ross, IBM Research

Page 49: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Beyond the next transistor: Exploratory Memory

SL m-1

SLm+1

SLm

WLn-1

WLn+1

WLn

Everyone is looking for a dense (cheap) crosspoint memory.It is relatively easy to identify materials that show bistable hysteretic behavior (easily distinguishable, stable on/off states).

Page 50: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Relative Maturity of Nonvolatile Memory Technologies

02468

101214161820

ProductSampling

Development Single CellDemo

Charts, NoParts

Tec

hn

olo

gy

Ch

amp

ion

s (C

om

pan

ies)

Page 51: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Smaller projects are also exploring non-volatile memory based on …

Perovskites

Chalcogenides

Organic materials

Page 52: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Beyond the Next Transistor“Millipede” Storage

Page 53: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

How will we manufacture at the nanoscale?

Page 54: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Carbon Nanotubes?

STM Image

Page 55: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Ti Ti Ti

Al AlAppl. Phys. Lett. 80, 3817 (2002)

dox=15nm

Carbon Nanotube Transistor

Page 56: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Comparison with silicon

transconductance

threshold voltage

channel length

gate oxide thickness

p-MOSFET a) p-CNFET

50nm

1.5nm ~15nm

2300mS/mm650mS/mm

-0.2V -0.5V

subthreshold slope 70mV/dec 130mV/dec

IOn/IOff ~106106 - 107

260nm

drive current 2100mA/mm650mA/mm(Vg-Vt=-1.0V)

a) R. Chau et al. Proceedings of IEDM 2001, p.621

Page 57: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

VS<VG<VD

VS

VD

VG

Nanotube Infrared Emitter

Page 58: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Nanotube Technology ?

CNTAu

100µm

How do you get from here to there?

Plenty of room for improvement !

No new architecture !

Page 59: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Establishing a Technology

Understanding:Electrostatics, electrodynamicsScalability (ballistic? contact-dominated transport ?)Contacts, dopingGate insulator, interface traps?High yield, selective growth/synthesis of nanotubes with correct electrical properties (single-wall, diameter, chirality)

Engineering:Device structure with minimized parasitic resistance and capacitanceFabrication processes leading to high device density (e.g. size of contacts commensurate with gate length, means to connect one device to another)Demonstrate device/circuits which satisfies ALL performance metrics (not just some metrics)Manufacturing tools and infrastructure, integration with siliconReliability...

Page 60: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Molecules = Small ?

L >2.5 – 3 nm

Si FET Molecular Device

TSi=7nm Lgate=6nm

Source Drain

Gate

B. Doris et al., IEDM , 2002.

All devices are governed by electrostatics and eventually limited by tunneling- difficult to be much smaller than 2 - 3 nm

Page 61: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Building Molecular Structures to Study the Science

Si

SiO2

+-

+ + +- - -

electrolytesolution

pipette orneedle

also workingelectrode

Vg

Electrochemically GateMolecular Junction

Pt coating

TiAu

Allimit assembly to electrode

sidewall

n+ Si

SiO2

Source Drain

R R R R R R

R' R' R' R' R' R'

Gate

Lipid-like membrane– Self-assembled at air-water interface

– Langmuir-Schaeffer transferIn-situ polymerization

– conjugated chain (schematic)

– wide band conductor

– end-to-end channel Hydrophobic binding - gate insulator

Page 62: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Chemistry to Covalently Bind Molecules to Substrates

Choose Length of alkyl chainDepending on desired function

C

Si

C

SiO OO O O

C

Si

C

SiOO O O

C

Si

C

SiOO O O

C

Si

C

SiOO O O

OOH

OOH

OOH

OOH

OOH

OOHO

OHO

OH

SiO2

Si (intrinsic or doped)SiO2

Si (intrinsic or doped)

SiSiO OO O O

SiSiOO O O

SiSiOO O O

SiSiOO O O

SiSiO OO O O

SiSiOO O O

SiSiOO O O

SiSiOO O O

SiO2

Si (intrinsic or doped)

ORCH2

Si

CH2

SiO OO O O

CH2

Si

CH2

SiOO O O

CH2

Si

CH2

SiOO O O

CH2

Si

CH2

SiOO O O

OH OH OH OH OH OH OH OH

SiO2

Si (intrinsic or doped)

oxidation

reduction

Demonstratingnow

esterifactionwith molecule

having alcoholfunctionality

esterifactionwith molecule

having carboxylicacid functionality

SiO2

Si (intrinsic or doped)

= molecule of interest

C

Si

C

SiO OO O O

C

Si

C

SiOO O O

C

Si

C

SiOO O O

C

Si

C

SiOO O O

OO

OOO

OO

OO

OO

OO

OO

O

Water Subphase

OH

OH

OH

OOH

OOH

OOH

OOH

OC C C C C

O OH O OH O OH O OH O OH

C

O OH

UV

"backbone"

Water Subphase

SubstrateSubstrate

Substrate

(1) (2) (3)

Page 63: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

“Layer-by-Layer” Growth of Conjugated Molecules

• Grow long conjugated molecules that would otherwise be insoluble to span gap between electrodes• Combine different molecules or oligomers for functionality

Au

SS S S S S S S S Br

O O O O

SS S S S S S S S Br

O O O O

SS S S S S S S S Br

O O O O

Electron-donating/Electron-accepting Reduction-oxidation active centers

AuN N

N NZnS SS

BrS

S

+Au

SS

S S SBr

SS

S S SBr

SS

S S SBr

Tailor end functionalityto assemble on oxide, metal, or semiconductor surface

Au

SS

SBr

SS

SBr

SS

SBr

+ SR3Sn

SAu

SS

S S S

SS

S S S

SS

S S S

NBS

“Double FET”with floating electroden+ Si

SiO2

SS

S S S

SS

S S S

SS

S S S

SS

SSS

SS

SSS

SS

SSS

growmetal

Page 64: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Ligand to bind to desired

substrate surface

Addmetal-metal

Addligand

Addmetal-metal

Addligand

RhRhO

NN NN

OO O

Rh RhO

N NN N

O O O

N

N

RhRhO

NN NN

OO O

Rh RhO

N NN N

O O O

N

N

N

N

N

N

N

NSi

Si

Si

RhRhO

NN NN

OO O

Rh RhO

N NN N

O O O

N

N

RhRhO

NN NN

OO O

Rh RhO

N NN N

O O O

N

N

NS

NS

Au

N

N

N

N

Layer 1 Layer 2

N N

N,N'-di(p-anisyl)formamidinate

NC

N

HMeO OMe=

• Tailor head group of ligand to bind to particular substrate surface

• Tailor end group to templatemetal-metal bonded unit

• Choose M-M bondM = V, Nb, Cr, Mo, W, Tc, Re, Fe, Ru,

Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag …

• Choose ligand to bridge M-M bonded units to tailor:

• Electronic coupling between dimetal units

• Electrochemistry• Solubility• Structure ….

Leq

Leq Leq

Leq

MLeq Leq

Leq Leq

M LaxLaxLayer-By-Layer Growth of Metal-Metal Bonded Compounds

Page 65: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Beyond the Next TransistorMolecular Cascade Logic

A.J. Heinrich, C.P. Lutz, J.A. Gupta, D.M. Eigler Science 2002

Page 66: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

We are Just Getting Started!

Page 67: Designing Nanoscale Materials Lecture Series by 2004 Debye ...nanoparticles.org/pdf/CBM1.pdf · Lecture Series by 2004 Debye Institute Professor Christopher B. Murray IBM Research

Nanotechnology Definition Revised

The ability to design and control the structure of an object on all length scales – from the atomic to the

macroscopic – reliably and repeatedly in a manufacturing environment.