plasma nanotechnology: from microelectronics and discovery of carbon nanotubes to

Kostya (Ken) OstrikovCEO Science Leader, Director, Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, and Honorary Professor, University of Sydney, AUSTRALIA

Plasma Nanotechnology: from Microelectronics and

Discovery of Carbon Nanotubes to Self-Organized

Nanodevices and Safe Nanotech of the Future

is a multidisciplinary subfield at the cutting edge of plasma

physics, nanoscience, surface science, astrophysics, materials

science and engineering, and structural chemistry, which aims

to elucidate specific roles and purposes of the plasma

environment in assembling nano-things in natural, laboratory

and technological situations and find ways to bring this plasma-

based assembly to the deterministic level.

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Plasma* AND Fusion*

Plasma* AND Astro*

Plasma* AND Dust*

Plasma* AND Nano*

Plasma* AND Chemistry*

5 out 25 top cited

in NANO!!!

area we work in

Some examples of lab-based

highly-controlled synthesis of

nanoscale objects

35-50 nm

Architecture and hierarchically arrange complex functional

nanoscale objects in “streets”, “suburbs”, and “cities” and

then reconnect them at the expected density of integration!

Grand challenge

Electronic Photonic

Bio-

Ag Islands

Si

insulator

Incident light

Amorphous material

Scientific approach: “Architecture” – Order –

Make uniform – Connect

Extremely difficult to do for very small

nanostructures (e.g., QDs)

Poor ordering … Unpredictable

shapes…

Uncontrollable behaviour …

REASON:

LARGE (>100 nm) NANOPARTICLES ARE

TRAPPED IN ANY STATE THEY WERE CREATED

SMALL (<10 nm) NANOPARTICLES

RETURN TO EQUILIBRIUM SHAPE *

* at least to the next available metastable state closer to equilibrium

Operating under far from equilibrium

conditions [using the laws of kinetics]

Reaching the normally „unreachable‟ less

stable states [be quick!]

Tailoring the barriers [keep the structure!]

Solution

Non-equilibrium Nano-

architectronics: APPROACH

10

Low temperature plasmas: a unique

non-equilibrium system

Neutral

Gas

Ions

Electrons

N

0.025 eV 2 eVEnergy, W

0

• Electrons not in thermal equilibrium with the ions or neutrals

• High Te dissociates gas

• Low TG and T+ protects substrates

• Negative charge on surfaces protects them from high

electron energy

Higher complexity system – good for self-organization

(more effective driving forces)

Te >> Ti > Tn Nn >> Ni ~ Ne

Virtually unlimited choice of BUs and WUs

Electric fields

Long-range Coulomb interactions

Polarization interactions

Isotropic vs anisotropic pressure

Non-equilibrium cooling/heating )

Surface stresses due to ion bombardment

Charge, termination etc. – control of surface energy

Unusual chemical reactivity – plasma etching

MORE UNIQUE FEATURES

PLASMA – COMMON

INDUSTRIAL TOOL

So, what can the plasma do for nanotech?

FOR STARTERS: CNTs DISCOVERED

IN A PLASMA

http://www.nano-lab.com/nanotube-image.html

Unique vertical alignment of CNTs!

Z. Ren et al Science 1998: vol. 282. no. 5391, pp. 1105 - 1107 .

Plasma

routeNeutral

route

Plasma (nano)etching – common industrial process!

PPAP 4,

612 (2007)

Highly-unusual metastable nanomaterials and nanophases

S. Komatsu, JPD, v. 40, 23 Apr 2007

Ie+Ii

Us

Ie+Ii=0

ffloat

Controlled delivery and redistribution of building units

Control of surface energetics, diffusion, desorption, etc.

,4/34/3 b

s

k

eUT

Substrate heating due to ion flux, φ [ML/s]

Effective substrate temperature in presence of an ion flux: T + δT

NON-Equilibrium heating and stress

ENABLING A DETERMINISTIC APPROACH

Single crystal, cubic shape silicon

nanocrystals produced in a non-equilibrium

plasma [U. Kortshagen et al., JNN 9, 39

(2007)]

Non-equilibrium plasma turns

things upside down No plasma (no H-termination)

Si cube is least stable, “unwanted”

Effective H-termination

Si cube is most stable, “wanted”

A. Barnard, P. Zapol, J. Chem.

B. Phys. 121, 4276 (2004)

T. Hawa, M. R. Zachariah,

J. Phys. Chem. C 112,

14796 (2008)

I. SHAPING

Si (100) Si (111)

Tailoring Si nanocones and nano-

pyramids in Ar + H2 plasma

(S. Y. Huang, S. Xu, I. Levchenko,

K. Ostrikov, 2009)

Pseudo Light IV curve without the effect of Rs

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t=30 min; Vb=0.

Pseudo Light IV curve without the effect of Rs

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Voc= 347 mVPseudo Light IV curve without the effect of Rs

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Ar : H2 = 1 : 3;

Pin = 2.0 kW;

T = 300 K; t=30min;

Vb= - 50V

Voc= 453 mV

PV – collaboration with PSAC NIE/NTU [S. Xu et al.]

What does this mean for PV solar cells?

Tailoring iron oxide nanowires and nanobelts [U. Cvelbar, K.

Ostrikov, Crystal Growth Design 8, 4347 (2008)]

Challenge: controlling nanostructure shapes

Solution: control by electric conditions on the surface

[APL 94, 211502 (2009)]

Tailoring microplasma nanofabrication: from nanostructures to

nanoarchitectures [Mariotti & Ostrikov, J. Phys D 42, 092002 (2009)]

Predicting nucleation sites

[Levchenko, Cvelbar, Ostrikov (June

2009), submitted to APL]

II. ARRANGING

Self-organization of Ni/Si nanodots under

plasma exposure [APL 93, 183102 (2008)]

Simultaneous Ni catalyst saturation [I. Levchenko and

K. Ostrikov, Appl. Phys. Lett. 92 (2008)]

Arrows show larger

relative ion flux

More uniform CNT arrays !

3D self-organization– not the case in neutral gas

processes [Carbon 45, 2022 (2007)] !!!

S. Y. Huang, J. D. Long, S. Xu, K. Ostrikov (2008):

self-ordering of SiC nanoislands (electric ordering factors)

No plasma With plasma

Self-organization near thermodynamic equilibrium leads to

relatively simple geometries whereas self-organization far from

equilibrium leads to more complex geometries [Whitesides and

Grzbowski, Science 295, 2418 (2002)]

Self-Organized Carbon Connections

Between Ag Nanoparticles via

Atmospheric Microplasma Synthesis

[CARBON (Letters) 47, 344 (2009)]

III. CONNECTING

Also: Si NPs and realistic surface processes. Carbon,

in press (2009) doi:10.1016/j.carbon.2009.04.031

IEEE Trans Plasma Sci. 36, 866 (2008)

This will eventually lead to … nano-

architectured self-assembled nanoscale

systems

applications

Medicine

Re‟new‟wable

energy

Links to other academic and industrial areas

Astrophysics

Electrochem.

batteries

Coatings

ChemistryOpto-

electronics

Life

sciences

Nano-

devices

Photonics

Nano-

electronics

Integrated

circuitry

Plasma

physicsNano-

science

Materials

scienceSurface

science

Advanced

materials

Quantum

information

Sensors Bio-implants

Plasma

medicine

Environmental

remediation

Nanotools

Plasmonic

structuresDrug/gene

deliveryBiomarkers

LEDs

Lasers

Solar cells

Catalysis

Chemical

synthesis

Applications: some examples

Multipurpose CNTs

“Self-organised”

Nanoelectronics

Optoelectronics/PhotonicsUltra-nanoporous materials

BIOIMPLANTS

E-mail: Kostya.Ostrikov@csiro.au

GAS SENSORS

PV – collaboration with PSAC NIE/NTU [S. Xu et al.]

Si thin film solar cell

µc-Si

Si thin film solar cell

µc-Si

PV SOLAR CELLS Photo-active layers

TCO

Plasmonic arrays

Plasma control of nanostructured phases in nc-Si for PV solar cells

[Cryst Growth Design 9, 2863 (2009); Nanotechnology 20,

215606 (2009); J. Mater. Chem. (2009) DOI: 10.1039/b904227j]

Amorph phaseCryst phase

100oC

200oC

300oC

Onset of nanocrystallinity + nanophase control

Very high growth rates0 – 86% cryst phase

+ bandgap control

Also: 1) no hydrogen dilution possible! 2) excellent

transmittance in optical range

nc-Si : control of nanocrystalline phases, growth rates, and optical

bandgap [Cryst Growth Design 9, 2863 (2009); Nanotechnology 20,

215606 (2009); J. Mater. Chem. (2009) DOI: 10.1039/b904227j]

Challenges, grand or small,

all lead to breakthrough

Hydrogenation of graphene (inert and

conducting) in Ar + H2 DC plasma

leads to graphane (dielectric)

Image: A. Savchenko, Science 323, 589 (2009)

Big challenges:

1) Epitaxial self-assembled graphene

2) Precise control of surface

energetics

3) Switch-over between TD and

kinetic modes

Transforming matter by controlled surface hydrogenation

(“what amazing things can the plasma do!”)

D. C. Elias et al., Science 323, 610 (2009)

Levchenko, Ostrikov, Xu, JPhysD 42, 125207 (2009)

Graphene Nanoribbons (GNRs):

L. Jiao et al. Nature 458, 877 (2009)

Ar plasma (~10s)

A plasma knife can cut the nanotubes to create GNRs

Big challenges:

1) understanding ion-CNT

interactions

2) How to make it precise and

“gentle”?

CA ~

150 – 170o

Superhydrophobic a-C/CNT composites via ion bombardment

[Han, Tay, Shakerzadeh, Ostrikov, APL 94, 223106 (2009)]

Energetic (~1 kV) ions are focused by the CNTs, push the Ni catalyst particle

down the channel and then create a-C “caps”. Water droplets are suspended

and do not fall down the inter-CNT gaps. Array parameters do matter!

Plasma exposure of CNTs can even convert them

into diamond – caution and understanding needed!

E. Aydil et al, Uni Minnesota (Gordon Res. Conf. 2008)

Remote PECVD, 90% H2 + 10% CH4,

15 mbar, 400-650oC; 0.5 nm Al / 0.5-1

nm Fe / 10 nm Al 70% purity (30% a-C)

Metallic / Semicond = 1:2

J. Robertson et al. APL 93, 163911 (2008)

Challenges: chirality control; selective

elimination of metallic or semicond.

tubes

Control of SWCNTs

Example of solution: burning metallic SWCNTs

M. Keidar et al., Carbon

44, 1022 (2006);

K. Ostrikov and A. B. Murphy,

J. Phys. D 40, 2223 (2007)

But how to

select

any particular

chirality?

Solution: grow thinner SWCNTs much faster than others!

NEUTRAL CVD

PECVD PECVD

E. Tam and K. Ostrikov (June 2009); see

also APL 93, 261504 (2008)

NEUTRAL CVD

PECVD

K.V. Emtsev et al. Nature Mater. 8 (2009) 203.

Images: P. Sutter Nature Mater. 8 (2009) 171.

Towards epitaxial graphene

High-pressure Ar

atmosphere

Si sublimates leaving

exfoliated graphene behind

Control of Si sublimation through polarization effects:

the ionization theory approach [Phys Lett A 373, 2267 (2009)]

Si atoms tend to diffuse and evaporate faster than C.

Electric field/Polarizability – additional way to control!

GRAND CHALLENGES

1)

2)

3)

4)

5)

35nm 25nm 10nm 5nm 2.5nm 1nm

2010 2020 2030 2040

Monochroic Flux

Ultimate Controlled Beam Process for

Perfect No-Defect Hi-Speed Self-

Assembled films / Materials

Vertical/Lateral Atomically-controlled Depo/Etch Bio Molecular Manipulation

Device dimension

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DATABASE : Atom, Molecule Reaction / Surface Reaction / Mechanism

Compound Semiconductor Nano-scale Logic Device Molecular Device Atomic DeviceHigh Definition Flexible Display 3-Dimension Display Ubiquitous Display Projection in Brain

Health Care Chip Drug-Delivery system Bio-Mechanics-fusion Bio-Self-assembly Self-repairing Genome DeviceUltra Efficient Solar Cell Super Efficient Photoelectric/Thermoelectric conversion New Energy Source

Hi Precision / Hi Productivity / Large Area / Stable Production Technology

Environmental Detox Hi-Efficient Agricultural/Marine production Nano Detox Global Restoration

Hi-Efficient Manufac. Tool 1 Atom-Accurate Manufac. Tool Self Assemble Manufac. Tool

Principle of Species Generation Control Nano, μ - m scale, Lo - Hi Pressure, Gas/Liquid/Solid(Surface), Phase mix

Principle of Surface Reaction 1 Atom/Molecule Control Control of Functional Unit Organic/Bio Material

Principle of Selective Reaction/Self-Assemble Clarify & Realize of No-defect / Ultra Hi-Speed reaction

Defect Self-healing

Synergic Reaction in Large area

Top-down Process

Bottom-Up Process

Diagnostics Ultimate precise No Disturb. 3D Flash Diag. Nano struct./Elec.Charact. Diag. Prognostic Diag.

Simulation Ultimate correct Multi Scaled Time/Space Flash (intuitive） Algorithm

Development for Feedback Control Technology using Monitor and Simulation

Common Basic Technology

Engineering makes Seeds(Principle) to Production Technology

Monitor- ,Simulator - Friendly Reactor Design

Navigation Assist Process Tuning Pin-Point Control Pin-Point Design

JSAP/NEDO Roadmap:Plasma Process Technology

Plasma Electronics Division, JSAP

Ｚ

Diagnostics ・ Visualization support tool

Interactive type software

Linkage with experiments, experiment control (Validation of simulation)

Multi scale （Space, Time）Simulation

Collection & compile of Fundamental data（Cross-section, Potential, transport co. ,…）

Approximation・Modeling Technique including first-principle simulation

Molecule scale（Molecular dynamics）

Mesoscopic scale （Fluid・ Stochastic method）

Micro scale （Continuous model）

High speed algorithm

Rule mining (Estimation for law of physics & chemistry via simulation)

Learning・Adaptive

control software

Process Simulation

2010 2020 2030 2040

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Sub map for Plasma Process Technology

25nm 18 13 6 4.2 2.9 2.1 1.4 1.09Tr.Gate siza

<±1.0nm以下（Lower limitation）

±3.0nm ±2.0nmPrecise

etching

Wafer Quality(Yield)

Effect for Equipment Availability

(Productivity)

Fault Detection & Classification

Fault Prediction

Run-to-Run Control

In-Situ Control

Culture change

The PresentThe Present

EEC *Equipment Engineering Contribution

レシピ プロセス特性

Miniaturization

Real-time control

New field

Large wafer300mmΦ 450mmΦ

675mmΦLarge area

Tool control &

Operation technol.

Real time prediction of fluctuation Autonomous ajustment

Plasma for

Nano process

Atom, molecule

process control

Atom･Molec. Process

＋Self-assembled Reaction

2010 2020 2030 2040

レシピ プロセス特性

Model for process control

Fundamental database

（Crosssection, Reactivity,…）

Prediction・simulation Low damage

Very Edge control

Tool monitoring

Real-time monitoring

FDC/EES

Virtual Metrology

Fault Prediction

Real Time Feed Back

CMOS

Magetic, Organic, Bio, Ecology

Micro fabrication

・Thru via, both sides, 3D ・Large area, ・Ultra flatness ：～1nm

Ultra hi-speed, directional etching Si /Quartz: ～300 / ～30 um/min ～500 / ～50 um/min

・Low density ・Low temp/energy, Low damage, ・UV/VUV control

Max Aspect ration

50150 250 500MEMS

Plasma for MEMS fabrication・Ultra hi density Ne:～1016/cm3

Radical： ～1018/cm3

・Thermal plasma, ATP

Precise

Sensor, Mirror, Switch

Hi Integration

Fusion w/Semi, Optics

Revolutional

Robot, Bio, Ecology

Sub map for Plasma Process Technology

Plasma Nanoarchitectronics – a way towards

SAFE, CLEAN, and ENVIRONMENTALLY

FRIENDLY nanotechnology

Constantly raising concerns about nano-safety issues

Plasma nanotech offers safe, clean, and green solutions:

Vacuum processing – no human exposure

No chemical vaste (all “burns”)

Surface supported nanoparticles – nothing to inhale

Hazards “burn” yet no CO2

emission

CONCLUSIONS

Self-organized arrays/devices are vitally needed

Deterministic non-equilibrium nanoarchitectronics based

on guided self-organization is the way to achieve these goals

Non-equilibrium low-temp plasma environments offer

many exciting possibilities to enable determinism

Platform for future SAFE and GREEN nanotechnologies

A lot of exciting work ahead to solve the Grand

Challenges for the Science and Imagination!

Plasma – “nano-pioneer” (nano-etching, CNTs)

More details: Kostya.Ostrikov@csiro.au

Co NPs

DLC

nanocolumns

Magnetic control factors of self-organization

[Meletis and Jiang, JNN 6, 1-4 (2006)]

Solar cells: low dimensional single junction

The maximum open-circuit

voltage Voc is 522 mV, and the

corresponding fill factor is

80.8%.

Voc strongly depends on the r

the shape of the structure.

p-type Si

substrate

(a) Before

Plasma

p-type Si

substrate

(b) Plasma on

p-type Si substrate

p-(n)-type Si

(c) After

E

Solar cells: single junction

(a) Voc=116 mV;

FF=39.1%(b) Voc=287 mV;

FF=76.7%

(c) Voc=347 mV;

FF=77.4%

(d) Voc=453 mV;

FF=82.1%

(e) Voc=480 mV;

FF=79.2%

(b) Voc=522 mV;

FF=80.8%

Collaboration with IHPC – plasmonic enhancement

Size, density,

and arrangement

of metal NPs are

VERY important!

Akimov, Koh, Ostrikov,

Optics Express 17,

10195 (2009).

[a]

Nuclear fusion device (DPF) for making ZnO nanoparticles

100% made of ions and featuring room-temp PL !!!

Malhotra, Roy, Srivastava, Kant, Ostrikov [submitted to

J. Phys. D, May 2009]

OUTLINE:

1. PLASMA NANOSCIENCE - AREA WE WORK IN

2. GRAND CHALLENGE FOR NANOSCIENCE: INTRODUCING

NON-EQUILIBRIUM NANOARCHITECTRONICS

3. WHY PLASMA AND WHAT CAN PLASMA/IONS/E-FIELDS DO?

4. IMPLEMENTATION: TAILOR – ARRANGE – CONNECT

5. MORE RESULTS AND EXAMPLES OF APPLICATIONS

6. SO, WHERE IS THE CUTTING EDGE AND WHERE WILL IT

LEAD TO?

Our International Network: > 15 countries

Uni Sydney, AUS

Zhejiang, ChinaNUS, IHPC, IMRE,

IME (Singapore)Rochester Uni

Technol, USA

Chartered

Semiconductors

MFG

Uni Sydney, AUSNTU, NIE

Singapore

SJTU, China Josef Stefan Inst,

Slovenia, EU

George

Washington

Uni, USA

Nagoya Uni, Japan

Plasma Nanotech

CoE

Ruhr-Uni,

Germany, EU

Kharkiv National Uni + Natl

Aerospace Uni, Ukraine

Uni Michigan,

USALHMTI, Belarus

Fudan Uni, China Huazhong Uni, China Uni Delhi, India

PNCA@

Nanocrystalline Si for PV solar cells applications

Cover image: J. Mater Chemistry (June 2009)

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