plasma nanotechnology: from microelectronics and discovery of carbon nanotubes to
TRANSCRIPT
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.
0 5 10 150
4
8
12
16
20
% o
f T
ota
l P
ap
ers
pub
lishe
d
Year (from 1990)
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
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.00 0.05 0.10 0.15 0.20 0.25
Voltage (V)
Cu
rren
t (A
/cm
2)
0.000
0.009
Po
wer
Den
sit
y (
W/c
m2)
Voc= 116 mV
Ar : H2 = 9 : 1;
Pin= 2.0 kW; T = 300K,
t=30 min; Vb=0.
Pseudo Light IV curve without the effect of Rs
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40
Voltage (V)
Cu
rren
t (A
/cm
2)
0.000
0.009
0.019
Po
wer
Den
sit
y (
W/c
m2)
Ar : H2=1 : 3;
Pin =1.5 kW;
T = 300 K; t =30 min;
Vb= - 50V
Voc= 347 mVPseudo Light IV curve without the effect of Rs
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.00 0.10 0.20 0.30 0.40 0.50
Voltage (V)
Cu
rren
t (A
/cm
2)
0.000
0.009
0.019
Po
wer
Den
sit
y (
W/c
m2)
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: [email protected]
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
Ou
tpu
tP
rod
uct
s, A
pp
lica
tion
De
velo
pm
en
tM
an
ufa
ctu
rin
g
tech
nolo
gy
Re
searc
hS
eed
s
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
Ou
tpu
tP
rod
ucts
, Ap
pli
cati
on
De
ve
lop
me
nt
Ma
nu
factu
rin
g
tech
no
log
y
Re
searc
hS
eed
sF
un
da
men
tals
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: [email protected]
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)
2007 2008 2009
100
200
300
400
500
600
Year
Vo
c (
mV
)
0
4
8
12
16
20
24
28
Jsc (m
A/c
m2)