Plasmas for additive manufacturingOLTP SeminarSee Y. Sui et al., Plasma Proc. Polym. 17, e20000009 (2020).
R. Mohan SankaranDonald Biggar Willett Professor in EngineeringDepartment of Nuclear, Plasma, and Radiological Engineering
Email: [email protected]: https://speclab.npre.Illinois.edu
2
additive manufacturing (AM) – a process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing technologies.
ASTM F2792-12a: Standard Terminology for Additive Manufacturing Technologies, 2013.
Subtractive vs. additive approaches to materials manufacturing
3
Subtractive:
Additive:
Material wasteage, relatively fast and easy, ideal for large parts
Slow and complex, enables intricate geometries, small parts
Examples of additive manufacturing
4
1980 1990 2000 2010
Williams, VTech
Greer, Caltech
Selective laser sintering: Fraunhofer Institute, 1995
Forced deposition modeling: Crump, 1988
Binder jetting: Sachs, MIT, 1993
Stereolithography: Kodama, Nagoya MIRI, 1980; Hull, 3D Systems Corp., 1984
FDM patent ends, 2009
Cold spray: 2000sSpee3D
Thin film printing approaches
5
Screen printing(Doctor’s blade)
(Gravure printing)
Inkjet printing(Aerosol jet printing)
Limited to a few metals (Ag, Cu, …)
Opportunities for plasmas in additive manufacturing
6
•Low-temperature•Gas-phase•Non-equilibrium chemistry•Conformal
PLASMA
NEW MATERIALS•Metals•Semiconductors
PROCESSING•Direct deposition•Hard/Soft SURFACE TREATMENT
•Hydrophilic/phobic•Functionalization
REMOVAL•Etching/sputtering•Corrections
MULTIPHASE•Liquids•Aerosols
Opportunities for plasmas in additive manufacturing
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•Low-temperature•Gas-phase•Non-equilibrium chemistry•Conformal
PLASMA
NEW MATERIALS•Metals•Semiconductors
PROCESSING•Direct deposition•Hard/Soft SURFACE TREATMENT
•Hydrophilic/phobic•Functionalization
REMOVAL•Etching/sputtering•Corrections
MULTIPHASE•Liquids•Aerosols
Potential strategies for plasma synthesis of printed structures
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DIRECT WRITE
Potential strategies for plasma synthesis of printed structures
9
DIRECT WRITE
( )
Potential strategies for plasma synthesis of printed structures
10
DIRECT WRITE
POST-PRINT
( )
11
I. Direct writea. Nanoparticle depositionb. Reduction of dispersed metal salts
II. Post-printa. Sinteringb. Conversionc. Beyond metals
12
I. Direct writea. Nanoparticle depositionb. Reduction of dispersed metal salts
II. Post-printa. Sinteringb. Conversionc. Beyond metals
Synthesis of nanoparticles from liquid aerosol droplets
13
Au3+ Au
e-
P. Maguire et al., Nano Lett. 17, 1336 (2017).
Plasma Droplet
Plasma jet printing of metals from liquid aerosols
14 A. Dey et al., J. Vac. Sci. Technol. B 37, 031203 (2019).
Space Foundry Inc., Moffett Field, CA
15
I. Direct writea. Nanoparticle depositionb. Reduction of dispersed metal salts
II. Post-printa. Sinteringb. Conversionc. Beyond metals
Localized conversion of thin films of metal precursor and polymer
16
Aqueous solution of polymer and metal salt
Localized conversion of thin films of metal precursor and polymer
17
Aqueous solution of polymer and metal salt Doctor’s blade coating (spin coating, etc.)
Electrical characterization of AgNO3/PVA films
18
-4 -2 0 2 4-6
-4
-2
0
2
4
6
As-deposited film Plasma exposed
Cur
rent
(x10
-8 A
)
Voltage (V)
R=82 MΩρ=122 kΩ-cm*
Large resistance may be due to poor morphology (not completely percolating).
At higher Ag precursor loading, solutions are unstable.
2-point probe measurement
3 μm
ACS Appl. Mater. Inter. 6, 2099 (2014).
*Ag: 1.59 μΩ-cm
Polyacrylic acid as a polymer matrix
19
Ag+
PAAr:Ag+ = 1:0.32
ACS Appl. Mater. Inter. 6, 2099 (2014).
Polyacrylic acid as a polymer matrix
20
Ag+1:0.32
1:0.64
Percolating network
500 nm
500 nm
ACS Appl. Mater. Inter. 6, 2099 (2014).
Cross-sectional EDS of microplasma-reduced Ag-PAA films
21
20 µm
20 µm
20 µm
20 µm
Unreduced sample Reduced region
ACS Appl. Mater. Inter. 6, 2099 (2014).
Proposed electric migration mechanism for surface-rich Ag layer
22
𝐸𝐸
Cathode
Anode
Ag-PAA film
Microplasma jet
ACS Appl. Mater. Inter. 6, 2099 (2014).Plasma Chem. Plasma Proc. 36, 295 (2016).
Electrical conductivity depends on initial film thickness
23
Film acts as a “reservoir” for the reduction and formation of Ag at the surface.
-1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
-10
-5
0
5
10
10 µm 20 µm 40 µm 80 µm
Cur
rent
(µA)
Voltage (V)10 20 30 40 50 60 70 80 90
101
102
103
Res
istiv
ity (Ω
-cm
)Film thickness (µm)
1:0.32 PAAr:Ag
*Ag: 1.59 μΩ-cm*ITO: 0.1 Ω-cm*Ag NP inks: 5 μΩ-cm-10 Ω-cm
ACS Appl. Mater. Inter. 6, 2099 (2014).
Integration of reduced Ag-PAA films with elastomeric PDMS substrates
24 ACS Macro. Lett. 6, 194 (2017).
Ag-PAA PDMSMix & centrifuge
Blade casting
Microplasma reduction (AC)
AgNO3PAA
Conductivity as a function of strain in Ag-PAA on PDMS films
25
0 5 10 15 20 25 30 35 40 450
20
40
60
80
100
33%
27%
R/R
0
Strain (%)
AuPDMS
0%
Prestrained
15%
27%
33%
ACS Macro. Lett. 6, 194 (2017).
SEM analysis of microstructure during straining
26
17% 35%
PrestrainedSt
rain
ing
dire
ctio
n
As-deposited
ACS Macro. Lett. 6, 194 (2017).
27
I. Direct writea. Nanoparticle depositionb. Reduction of dispersed metal salts
II. Post-printa. Sinteringb. Conversionc. Beyond metals
Need for sintering of printed nanoparticle inks
28
> 200 oC
O. Kravchuk et al., NANO 2017, 317 (2018).
< 150 oC
Plasma sintering
29
S. Wunscher et al., J. Mater. Chem. 22, 24569 (2012).
S. Ma et al., Appl. Surf. Sci. 293, 207 (2014).
30
I. Direct writea. Nanoparticle depositionb. Reduction of dispersed metal salts
II. Post-printa. Sinteringb. Conversionc. Beyond metals
Plasma conversion: Metal-organic decomposition (MOD) inks
31 Y. Farraj et al., ACS Appl. Mater. Inter. 9, 8766 (2017).
< 60 oC
Plasma conversion: Metal-organic decomposition (MOD) inks
32 Y. Farraj et al., ACS Appl. Mater. Inter. 9, 8766 (2017).
< 60 oC
Plasma conversion: Metal salts dispersed in aqueous solutions
33 J. Vac. Sci. Technol. A 36, 051302 (2018).
AgNO3 Ag
Plasma conversion: Metal salts dispersed in aqueous solutions
34 Adv. Mater. Technol. 4, 1900119 (2019).
< 77 oC < 138 oC
Plasma conversion: Metal salts dispersed in aqueous solutions
35 Adv. Mater. Technol. 4, 1900119 (2019).
Tg ~ 75 oC 80 oC 100 oC(melting)
Characterization of printed and plasma converted metals
36 Adv. Mater. Technol. 4, 1900119 (2019).
Cu:
Au:
Potential mechanism for plasma conversion of printed metal salt films
37 Adv. Mater. Technol. 4, 1900119 (2019).
Sn2+
Sn0
Sn2+
Sn0
38
I. Direct writea. Nanoparticle depositionb. Reduction of dispersed metal salts
II. Post-printa. Sinteringb. Conversionc. Beyond metals
Plasma conversion (reduction) of graphene oxide
39 Adv. Mater. Technol. 4, 1900834 (2019).
Characterization of plasma-converted rGO
40 Adv. Mater. Technol. 4, 1900834 (2019).
Atmospheric-pressure dielectric barrier (DBD) reactor with cold wall substrate heater
41
6 mm
5 mm
4 mm
3 mm
Electrode gap
Plasma conversion of spin-coated ammonia borane to h-BN thin films (Ar only)
42
1100 1200 1300 1400 1500 1600
1000 °C
800 °C
650 °C
Inte
nsity
(A.U
.)
Raman shift (cm-1)
Micro Raman spectroscopy:
ACS Appl. Mater. Inter. 10, 43936 (2018).
500 1000 1500 2000 2500 3000 3500
Bulk h-BN reference
Inte
nsity
(A.U
.)
Raman shift (cm-1)
Ammonia borane
1366 cm-1
Plasma conversion of spin-coated ammonia borane to h-BN thin films (Ar only)
43
1100 1200 1300 1400 1500 1600
1000 °C
800 °C+ plasma
800 °C
650 °C
650 °C + plasma
Inte
nsity
(A.U
.)
Raman shift (cm-1)500 1000 1500 2000 2500 3000 3500
Bulk h-BN reference
Inte
nsity
(A.U
.)
Raman shift (cm-1)
Ammonia borane
1366 cm-1
Micro Raman spectroscopy:
ACS Appl. Mater. Inter. 10, 43936 (2018).
Plasma conversion of spin-coated ammonia borane to h-BN thin films (Ar + H2)
44
1100 1200 1300 1400 1500 1600
800 oC+ plasma
800 oC
650 oC
650 oC+ plasma
500 oC + plasma
500 oC
Inte
nsity
(A.U
.)
Raman shift (cm-1)
Micro Raman spectroscopy:
ACS Appl. Mater. Inter. 10, 43936 (2018).
Assessment of film crystallinity by Raman analysis
45
400 600 800 1000 12000
10
20
30
40
50
60
70
(a)(b)
(c)
(f)
(d) Metal CVD
Si CVD
Plasma
FWH
M (c
m-1
)
Temperature (oC)
Thermal
(e)
𝐿𝐿𝑎𝑎 = 1417Γ1/2
− 8.7*
FWHM (Γ1/2) is inversely rated to crystalline domain size (La):
(a)S. Behura et al., J. Am. Chem. Soc. 137, 13060 (2015).(b)S. Behura et al., ACS Nano 11, 4985 (2017).(c)R. Y. Tay et al., Appl. Phys. Lett. 106, 101901 (2015).(d)L. Song et al., Nano Lett. 10, 3209 (2010).(e)J-H. Park et al., ACS Nano 8, 8520 (2014).(f) S. M. Kim et al., Nat. Comm. 6, 8862 (2015).
*R. Nemanich et al., Phys. Rev. B 23, 6348 (1981).
ACS Appl. Mater. Inter. 10, 43936 (2018).
Proposed mechanism for plasma-enhanced chemical film conversion (PECFC)
46
S. Frueh et al., Inorg. Chem. 50, 783 (2011).
S. Sriraman et al., Nature 418, 62 (2002).J. C. Angus et al., Science 241, 913 (1988).
Proposed mechanism for plasma-enhanced chemical film conversion (PECFC)
47
S. Frueh et al., Inorg. Chem. 50, 783 (2011).
400 500 600 700 800
Ar/H2 background (80:20)Hα
Inte
nsity
(A.U
.)
Wavelength (nm)
Ar background
ACS Appl. Mater. Inter. 10, 43936 (2018).
Demonstration of h-BN films as gate dielectric in 2D device
48
-30 -20 -10 0 10 20 300.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
without h-BN
Vds = 100 mV
I ds
(µA )
Vg (V)
x 10
with h-BN
Without h-BN With h-BN0
5
10
15
20
25
Mob
ility
(cm
2 /Vs)
-0.10 -0.05 0.00 0.05 0.10
-1.0
-0.5
0.0
0.5
1.0 +100 V +90 V +80 V +70 V +60 V +50 V +40 V +30 V +20 V +10 V 0 V
I ds
(µA )
Vds (V)
Gate voltage
ACS Appl. Mater. Inter. 10, 43936 (2018).
Extending PECFC to other layered materials: MoS2 from (NH4)2
2+MoS42- (ATM)
49 J. Vac. Sci. Technol. 38, 063006 (2020).
340 370 400 430In
tens
ity (A
.U.)
Raman shift (cm-1)
as-converted
500 oC
800 oC
1000 oC
E12g
A1g
Spin-coated precursor film Plasma-enhanced conversion step High temperature annealing
Plasma induces nucleation, growth, and crystallization
50
340 370 400 430
Inte
nsity
(A.U
.)
Raman shift (cm-1)
Thermally-treated (500 oC)
Thermally-treated + annealed
E12g
A1g
J. Vac. Sci. Technol. 38, 063006 (2020).
Micro Raman spectroscopy:
Plasma induces nucleation, growth, and crystallization
51
340 370 400 430
Inte
nsity
(A.U
.)
Raman shift (cm-1)
Thermally-treated (500 oC)
Thermally-treated + annealed
Plasma-triggered + annealed E1
2g
A1g
J. Vac. Sci. Technol. 38, 063006 (2020).
Micro Raman spectroscopy:
Plasma-triggered film Annealed film
Precursor film
Ar/H2, 500 oC
Ar, 25 oC Ar, 1000 oC
Ar, 1000 oC
Thermally treated
Strain generation in MoS2 films
52
360 370 380 390 400 410 420 430 440
Plasma converted
Inte
nsity
(A.U
.)
Raman shift (cm-1)
A1g
E12g
Plasma converted+
annealed
ACS Appl. Energy Mater. 2, 5163 (2019).
236 234 232 230 228 226 224
S 2s
Mo 3d5/2
Nor
mal
ized
inte
nsity
(A.U
.)
Binding energy (eV)
PECFC (500 oC) Post thermal (1000 oC)
Mo 3d3/2
166 164 162 160
S 2p3/2
Nor
mal
ized
inte
nsity
(A.U
.)Binding energy (eV)
PECFC (500 oC) Post thermal (1000 oC)
S 2p1/2
X-ray photoelectron spectroscopy:
S:Mo ratio is constant!
Micro Raman spectroscopy:
Types of defects in MoS2
53
AFM characterization of plasma converted MoS2 films: evidence for rippling
54
PECFC (500 oC) Annealed (1000 oC)
RMS roughness: 1.7 nm RMS roughness: 0.5 nm
ACS Appl. Energy Mater. 2, 5163 (2019).
Plasma converted MoS2 as catalyst for hydrogen evolution reaction (HER)
55
-0.7 -0.6 -0.5 -0.4 -0.3 -0.2-20
-15
-10
-5
0
Bare Cu
Post thermal(1000 oC)C
urre
nt d
ensi
ty (m
A/cm
2 )
Potential (V vs. SHE)
PECFC(500 oC)
Polarization curves in 0.5 M H2SO4:
0 40 80 120 160 2000.00
0.05
0.10
0.15
0.20
0.25 As-grown High T
Cur
rent
den
sity
at 0
V v
s. S
HE
(mA/
cm2 )
Scan rate (mV/s)
Edges
Double layer capacitance:
ACS Appl. Energy Mater. 2, 5163 (2019).
Plasma converted MoS2 as catalyst for hydrogen evolution reaction (HER)
56
-0.7 -0.6 -0.5 -0.4 -0.3 -0.2-20
-15
-10
-5
0
Bare Cu
Post thermal(1000 oC)C
urre
nt d
ensi
ty (m
A/cm
2 )
Potential (V vs. SHE)
PECFC(500 oC)
Polarization curves in 0.5 M H2SO4:
0 40 80 120 160 2000.00
0.05
0.10
0.15
0.20
0.25 As-grown High T
Cur
rent
den
sity
at 0
V v
s. S
HE
(mA/
cm2 )
Scan rate (mV/s)
Edges
Double layer capacitance:
Sample Double layer capacitance Tafel slope Current at -0.5
V vs. SHE Site density TOF
(mF/cm2) (mV/dec) (mA) (1015/cm2) (H2 s-1 /surface site)
PECFC (500 oC) 1.25 91 18.7 24.3 2.4
Post thermal (1000 oC) 0.63 127 1.6 12.1 0.4
ACS Appl. Energy Mater. 2, 5163 (2019).
Unique features of plasmas for AM: Ability to chemically convert, not just heat/sinter Gas-phase species for nucleation/growth and crystallization Charged species for low-temperature dissociation, electric migration, and defect
generation
Challenges to overcome for AM: Lower processing temperatures even further for materials beyond metals Decrease resolution for direct write Integrate with existing tools for 3D fabrication
Take home messages
57
Acknowledgements
58
Funding:
Collaborators
CWRU
Chemical and Biomolecular Engineering:
• Craig Virnelson
• Prof. C.C. Liu
• Prof. Rohan Akolkar
Materials Science and Engineering:
• Dr. Amir Avishai
• Dr. Jonathan Cowen
• Dr. Danqi Wang
Electrical Engineering and Computer Science:
• Dr. Yongkun Sui (University of Colorado Boulder)
• Prof. Christian Zorman
Alumni
• Carolyn Richmonds (Ph.D. candidate, Northwestern
University)
• Dr. Seung Whan Lee (NAFRI)
• Megan Witzke (Exxon Mobil, New Jersey)
• Brittany Bishop (Ph.D. candidate, University of
Washington)
• Dr. Souvik Ghosh (Intel)
• Evan Ostrowski (Ph.D. candidate, Princeton University)
• Dr. Tianqi Liu (Chinese Academy of Science)
• Ryan Hawtof (Ph.D. candidate, MIT)
Current group members
• Souvik Bhattacharya (Ph.D. candidate)