Plasma Nanotechnology: From Microelectronics And Discovery Of Carbon Nanotubes To

Plasma Nanotechnology: from Microelectronics and Discovery of Carbon Nanotubes to Self-Organized Nanodevices and Safe Nanotech of the Future Kostya (Ken) Ostrikov CEO Science Leader, Director, Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, and Honorary Professor, University of Sydney, AUSTRALIA

% of Total Papers published

5 out 25 top cited in NANO!!! 20

Plasma* AND Fusion* Plasma* AND Astro* Plasma* AND Dust* Plasma* AND Nano* Plasma* AND Chemistry*

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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 plasmabased assembly to the deterministic level.

Some examples of lab-based highly-controlled synthesis of nanoscale objects

35-50 nm

Grand challenge Architecture and hierarchically arrange complex functional nanoscale objects in “streets”, “suburbs”, and “cities” and then reconnect them at the expected density of integration!

Electronic

Photonic

Bio-

Incident light Ag Islands Amorphous material

insulator Si

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

Solution

Non-equilibrium Nanoarchitectronics: APPROACH  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!]

Low temperature plasmas: a unique non-equilibrium system N Electrons Neutral Gas Ions

0.025 eV

• • • •

2 eV

Energy, 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 10 electron energy

MORE UNIQUE FEATURES Te >> Ti > Tn

Nn >> Ni ~ Ne

 Higher complexity system – good for self-organization (more effective driving forces)       

Electric fields Long-range Coulomb interactions Polarization interactions PLASMA – COMMON Isotropic vs anisotropic pressure INDUSTRIAL TOOL Non-equilibrium cooling/heating ) Surface stresses due to ion bombardment Charge, termination etc. – control of surface energy  Virtually unlimited choice of BUs and WUs Unusual chemical reactivity – plasma etching So, what can the plasma do for nanotech?

FOR STARTERS: CNTs DISCOVERED IN A PLASMA

Unique vertical alignment of CNTs! Neutral route

Plasma route

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

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

Plasma (nano)etching – common industrial process!

PPAP 4, 612 (2007)

Highly-unusual metastable nanomaterials and nanophases

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

 Controlled delivery and redistribution of building units  Control of surface energetics, diffusion, desorption, etc.

Ie+Ii

Us

Ie+Ii=0

ffloat

NON-Equilibrium heating and stress

eU s 3 / 4 3 / 4 T    , kb Substrate heating due to ion flux, φ [ML/s]

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

ENABLING A DETERMINISTIC APPROACH

I. SHAPING

Non-equilibrium plasma turns things upside down No plasma (no H-termination)

Si cube is least stable, “unwanted” Effective H-termination

Single crystal, cubic shape silicon nanocrystals produced in a non-equilibrium plasma [U. Kortshagen et al., JNN 9, 39 (2007)]

Si cube is most stable, “wanted” A. B.

Barnard, P. Zapol, J. Chem. Phys. 121, 4276 (2004)

T. Hawa, M. R. Zachariah, J. Phys. Chem. C 112, 14796 (2008)

Tailoring Si nanocones and nanopyramids in Ar + H2 plasma (S. Y. Huang, S. Xu, I. Levchenko, K. Ostrikov, 2009)

Si (100)

Si (111)

PV – collaboration with PSAC NIE/NTU [S. Xu et al.] What does this mean for PV solar cells?

0.02 0.015 0.01

0.04

0.03 0.025 0.02

0.009

0.015 0.01

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Voltage (V)

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0 0.00

0.019

0.035 0.03 0.025 0.02

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0.015 0.01 0.005

0.005

0.05

Voc= 453 mV

0.019

0.035

0.005 0 0.00

Voc= 347 mV

Current (A/cm 2)

Current (A/cm 2)

0.03 0.025

Pseudo Light IV curve w ithout the effect of Rs

Power Density (W/cm2)

Voc= 116 mV

Current (A/cm 2)

0.035

Pseudo Light IV curve w ithout the effect of Rs

0.009

Power Density (W/cm2)

0.04

Power Density (W/cm2)

Pseudo Light IV curve w ithout the effect of Rs

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0.30

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Voltage (V)

Ar : H2=1 : 3; Ar : H2 = 9 : 1; Pin =1.5 kW; Pin= 2.0 kW; T = 300K, T = 300 K; t =30 min; t=30 min; Vb=0. Vb= - 50V

0 0.00

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0.30

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Voltage (V)

Ar : H2 = 1 : 3; Pin = 2.0 kW; T = 300 K; t=30min; Vb= - 50V

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)]

II. ARRANGING

Predicting nucleation sites

[Levchenko, Cvelbar, Ostrikov (June 2009), submitted to APL]

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)] !!!

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)]

No plasma

With plasma

S. Y. Huang, J. D. Long, S. Xu, K. Ostrikov (2008): self-ordering of SiC nanoislands (electric ordering factors)

III. CONNECTING

Self-Organized Carbon Connections Between Ag Nanoparticles via Atmospheric Microplasma Synthesis [CARBON (Letters) 47, 344 (2009)]

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 … nanoarchitectured self-assembled nanoscale systems

applications

Links to other academic and industrial areas Materials Surface Quantum science science information Re‟new‟wable energy Photonics Plasma Life Nanophysics sciences science NanoAstrophysics electronics Chemistry OptoMedicine electronics Sensors Advanced Integrated Plasma materials circuitry medicine

Nanodevices

Bio-implants Nanotools

Lasers Coatings Electrochem. Environmental Plasmonic batteries remediation structures Chemical Solar cells Drug/gene LEDs synthesis delivery Catalysis Biomarkers

Applications: some examples “Self-organised” Nanoelectronics

Multipurpose CNTs

Optoelectronics/Photonics

Ultra-nanoporous materials

GAS SENSORS BIOIMPLANTS

E-mail: [email protected]

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

TCO µc-Si

Si thin film solar cell

PV SOLAR CELLS

Photo-active layers

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]

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] 100oC

Very high growth rates

0 – 86% cryst phase + bandgap control

200oC Amorph phase

Cryst phase

300oC

Also: 1) no hydrogen dilution possible! 2) excellent transmittance in optical range Onset of nanocrystallinity + nanophase control

Challenges, grand or small, all lead to breakthrough

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)

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

A plasma knife can cut the nanotubes to create GNRs Ar plasma (~10s)

Graphene Nanoribbons (GNRs): L. Jiao et al. Nature 458, 877 (2009) Big challenges: 1) understanding ion-CNT interactions 2) How to make it precise and “gentle”?

Superhydrophobic a-C/CNT composites via ion bombardment [Han, Tay, Shakerzadeh, Ostrikov, APL 94, 223106 (2009)]

CA ~ 150 – 170o

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)

Control of SWCNTs

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

Challenges: chirality control; selective elimination of metallic or semicond. J. Robertson et al. APL 93, 163911 (2008) tubes

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

E. Tam and K. Ostrikov (June 2009); see also APL 93, 261504 (2008)

PECVD

NEUTRAL CVD

PECVD

Towards epitaxial graphene

High-pressure Ar atmosphere

Si sublimates leaving exfoliated graphene behind K.V. Emtsev et al. Nature Mater. 8 (2009) 203. Images: P. Sutter Nature Mater. 8 (2009) 171.

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)

JSAP/NEDO Roadmap:Plasma Process Technology Products, Application

Manufacturing technology

Development

Output

2010 Device dimension

35nm

2020 25nm

2030 10nm

2040

5nm

2.5nm

1nm

Compound Semiconductor Nano-scale Logic Device Molecular Device Atomic Device High 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 Device Ultra Efficient Solar Cell Super Efficient Photoelectric/Thermoelectric conversion New Energy Source Environmental Detox Hi-Efficient Agricultural/Marine production Nano Detox Global Restoration

Hi-Efficient Manufac. Tool

1 Atom-Accurate Manufac. Tool

Self Assemble Manufac. Tool

Engineering makes Seeds(Principle) to Production Technology Hi Precision / Hi Productivity / Large Area / Stable Production Technology Development for Feedback Control Technology using Monitor and Simulation Navigation Assist Process Tuning  Pin-Point Control  Pin-Point Design Monitor- ,Simulator - Friendly Reactor Design

Top-down Process Principle of Surface Reaction 1 Atom/Molecule Control Control of Functional Unit Organic/Bio Material Monochroic Flux Vertical/Lateral Atomically-controlled Depo/Etch Bio Molecular Manipulation

Seeds

Research

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

Bottom-Up Process Principle of Selective Reaction/Self-Assemble Clarify & Realize of No-defect / Ultra Hi-Speed reaction Ultimate Controlled Beam Process for Defect Self-healing Perfect No-Defect Hi-Speed SelfSynergic Reaction in Large area Common Basic Technology Assembled films / Materials 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

DATABASE : Atom, Molecule Reaction / Surface Reaction / Mechanism Plasma Electronics Division, JSAP

Sub map for Plasma Process Technology

Process Simulation Products, Application

Seeds

Manufacturing technology

2020

2030

Interactive type software Ｚ

2040

Learning・Adaptive control software

Diagnostics ・ Visualization support tool Linkage with experiments, experiment control (Validation of simulation) Rule mining (Estimation for law of physics & chemistry via simulation)

Molecule scale（Molecular dynamics） Mesoscopic scale （Fluid・ Stochastic method）

Multi scale （Space, Time） Simulation

Micro scale （Continuous model） Fundamentals

Research

Development

Output

2010

Approximation・Modeling Technique including first-principle simulation High speed algorithm Collection & compile of Fundamental data（Cross-section, Potential, transport co. ,…）

ピ

Sub map for Plasma Process Technology

Micro fabrication Atom, molecule process control

Plasma for Nano process 2010 Tr.Gate siza

Atom･Molec. Process ＋ Self-assembled Reaction

2020

25nm

18

13

2030 9

6

4.2

CMOS Precise etching

2040 2.9

2.1

1.4

1.0

Miniaturization Model for process control

±3.0nm

<±1.0nm以下 Prediction・simulation （Lower limitation） Fundamental database

±2.0nm

Low damage

Tool monitoring （Crosssection, Reactivity,…）

675mmΦ

Large area 300mmΦ

450mmΦ

Tool control & Operation technol.

Effect for Equipment Availability (Productivity)

Run-to-Run Control

Large wafer

Real-time control

In-Situ Control

FDC/EES Virtual Metrology Fault Prediction

Fault Prediction Culture change Fault Detection & Classification

Very Edge control Real-time monitoring

Real Time Feed Back

EEC *Equipment Engineering Contribution

Plasma for MEMS fabrication

The Present

Wafer Quality (Yield)

プロセス特性

Real time prediction of fluctuation

MEMS

Max Aspect ration

50

Autonomous ajustment

プロセス特性 Revolutional Precise 150 Hi Integrationレシピ 250 500 Robot, Bio, Ecology Fusion w/Semi, Optics Sensor, Mirror, Switch

Ultra hi-speed, directional etching

Si /Quartz: ～300 / ～30 um/min

・Thru via, both sides, 3D

New field

・Ultra hi density Ne:～1016/cm3 Radical： ～1018/cm3 ・Thermal plasma, ATP

・Large area,

～500 / ～50 um/min

・Ultra flatness ：～1nm

Magetic, Organic, Bio, Ecology ・Low density ・Low temp/energy, Low damage, ・UV/VUV control

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

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

More details: [email protected]

Magnetic control factors of self-organization [Meletis and Jiang, JNN 6, 1-4 (2006)] nanocolumns

Co NPs DLC

Solar cells: low dimensional single junction Plasma

p-(n)-type Si p-type substrate

(a) Before

Si

p-type substrate

(b) Plasma on

 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.

Si

p-type Si substrate

(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

Akimov, Koh, Ostrikov, Optics Express 17, 10195 (2009).

Size, density, and arrangement of metal NPs are VERY important!

Nuclear fusion device (DPF) for making ZnO nanoparticles 100% made of ions and featuring room-temp PL !!!

[a]

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 Rochester Uni Technol, USA Chartered Semiconductors MFG SJTU, China

Zhejiang, China

NUS, IHPC, IMRE, IME (Singapore)

NTU, NIE Singapore

Uni Sydney, AUS

Uni Sydney, AUS PNCA@

LHMTI, Belarus

Uni Michigan, USA

George Washington Uni, USA Fudan Uni, China

Ruhr-Uni, Germany, EU

Kharkiv National Uni + Natl Aerospace Uni, Ukraine Huazhong Uni, China

Josef Stefan Inst, Slovenia, EU Nagoya Uni, Japan Plasma Nanotech CoE Uni Delhi, India

Nanocrystalline Si for PV solar cells applications 28 24

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Cover image: J. Mater Chemistry (June 2009)

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