ESMD Faculty-Student Research Team:
Nanotechnology for Exploration and Science
Dr. Stephanie A. Getty
Prof. David D. Allred
NASA GSFCCode 541
Materials Engineering Branch
Applied Nanotechnology
Brigham Young University
Dept. of Physics and Astronomy
Students:
Jonathon Brame
Johnathan Goodsell
March 19, 2007
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NASA’s Exploration Initiative
Courtesy
NASA website
Carbon
Nanotubebased Magnetometer :
To the Moon, Mars
Magnetic analysis of geological
samples on Mars and the Moon
Orientation for manned expeditions
andLocation
Beyond
of mining resources
The Vision for Space Exploration calls for
humans to return to the moon by the end
of the next decade, paving the way for
eventual journeys to Mars and beyond.
March 19, 2007
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Projects ongoing in GSFC NanoDevices Group
– Strain-based NanoCompass
• GSFC: 541, 691
• BYU summer intern team: Prof. D. Allred, Johnathan
Goodsell, Jon Brame
– Electron gun for miniaturized mass spectrometer
• GSFC: 541, 553, 699
• Fisk University summer intern: Melissa Harrison
– Generalized strain sensors
• GSFC: 541, 660
• BYU summer intern team: Prof. D. Allred, Johnathan
Goodsell, Jon Brame
• Fisk University summer intern: Melissa Harrison
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Background Information:
Carbon Nanotubes
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Nanoelectronic Materials
Single-walled Carbon
Nanotubes
• Metallic or Semiconducting
– Difficult to control  trend toward
SWCNT network devices
• Electronic properties sensitive
to deformation
– Strain sensing
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Courtesy Smalley Group, Rice Univ.
Vapor-Liquid-Solid Growth
Feedstock gas  liquid alloy  solid nanostructure
SWCNTs:
MWCNTs:
•Catalyst = Fe(NO3)3:IPA or thin
film Fe
•Feedstock = CH4 and C2H4
•TG = 950°C, tG = 5-10 minutes
•Catalyst = thin film Al/Fe bilayer
•Feedstock = C2H4
•TG = 750°C, tG = 5-10 minutes
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NanoCompass
Thin Film Fe Catalyst
• High density
• Improved
cleanliness
TG = 950°C
TEM studies show
–SWCNTs
–MWCNTs
–bundles
20 nm
Johnathan Goodsell, Prof. David Allred, Prof. R. Vanfleet (BYU)
March 19, 2007
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Summary of Progress: SWCNT Growth
• Johnathan Goodsell
– Brigham Young University
– Mechanical Engineering Major
• Summer project: Optimize growth of
SWCNTs using thin film catalyst
– New process for GSFC
– Crucial for NanoCompass development
• Excellent results in only 8 weeks
– Contributed to IEEE Nano 2006 Presentation,
Cincinnati, OH, July 2006
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SWCNT NanoCompass for High
Spatial Resolution Magnetometry
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Technological Motivation
Mars
Applications:
• Magnetospheric Science
• Spacecraft Orientation
• Planetary Geomagnetism
Fluxgate Magnetometer:
• High sensitivity (nTesla)
• Low noise
but
• cm-scale resolution
• Limited materials supply
M. H. Acuna, Rev. Sci. Inst. 73, 3717 (2002)
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NanoCompass
NanoCompass Design
Single-Walled Carbon Nanotubes ● Ferromagnetic Needle
 Mech coupled to SWCNTs
 Deflected in Magnetic Field
● Au Electrodes
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Projected Specifications
NanoCompass
(estimated)
UCLA fluxgate (ST5)
Max Op Temp
~450°C
100°C
Sensor
Dimensions
10-5 cm x 10-5 cm on Si
(scalable)
4 cm x 4 cm x 6 cm
Sensor [Array]
Mass
1g
75 g
Sensor Op Power
10-3 - 10-2 mW
50 mW
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NanoCompass
NanoCompass Fabrication (to step 4)
Materials can be robust
to fabrication process
Next steps:
• Reduce electrode
spacing
• Reduce needle width
• Increase trench depth
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Future Work: Variability in Processing
• SWCNT device
electrically intact
• During magnetic field
testing, continuity lost
• Next prototype in
progress
Au
Au
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SWCNTs
Remnant
needle
Generalized Strain Sensing
Using SWCNTs
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Flexible substrates
• Parylene, PDMS are candidates
– Modular electromechanical strain sensors
– Modular field emitters
– Application-adaptive devices
• Parylene: vapor-phase coated polymer, highly
chemically resistant, excellent electronic
insulator
• PDMS: polydimethylsiloxane, two-part curable
elastomer, chemically resistant, good electronic
insulator – to be demonstrated in SWCNTs
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Device Transfer to Parylene
1. Fabricate SWCNT device
on rigid substrate to allow
electrical characterization
2. Deposit parylene
O2 plasma
3. Transfer to PDMS by
substrate removal
Wet etch
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Flexible Substrates
Parylene-bound SWCNT Strain Device
Jonathon Brame, Prof. David Allred (BYU)
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Flexible Substrates
Preliminary Results
• Large increase in
device resistance
with application of
strain, as expected
• Need to separate
contact effects
from piezoresistive
effects
• Need to evaluate
reproducibility
March 19, 2007
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The slope of the lines between 4µm stretch
sets indicates that the resistance increases
reversibly with increased strain.
NASA Headquarters
Summary of Progress: Parylene-bound SWCNT
Devices
• Jonathon Brame
– Brigham Young University
– Physics Major
• Summer project:
– Demonstrate transfer of SWCNTs to parylene substrates
– Test electromechanical response
• Preliminary fabrication and test completed in only 12
weeks
– Publication and presentation at MRS Fall Meeting, Boston,
November 2006
– “Strain-based Electrical Properties of Systems of Carbon
Nanotubes Embedded in Parylene,” Jon Brame, Stephanie
Getty, Johnathan Goodsell, and David Dean Allred,
Proceedings, Materials Research Society Fall 2006 Meeting.
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Status of Collaboration: GSFC-BYU Team
• BYU Team has major role in Mars Desert Research
Station (UT)
– In situ demonstration of NanoCompass operation
– Student-operated for outreach effort
– Relevant to manned missions to the Moon and Mars
• Joint proposal submitted to support NanoCompass:
– ROSES Planetary Instrument Definition and Development
– Decision Pending
• Building growth/characterization facility at BYU
– Correlated results, independent of location, important to the
CNT field
– Measurements of CNT response in extreme UV planned
– Possible applications in nanomaterial sensing for workplace
safety monitoring
March 19, 2007
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Acknowledgements
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Dr. Peter Wasilewski
Dr. Louis Barbier
Dr. Paul Mahaffy
Patrick Roman
Barney Lynch
Dr. Federico Herrero
Rusty Jones
Dr. Todd King
Rachael Bis
Michael Beamesderfer
Lance Delzeit
Prof. Gunther Kletetschka
Vilem Mikula
Tomoko Adachi
GSFC/Astrochemistry Laboratory
GSFC/Exploration of the Universe Division
GSFC/Atmospheric Experiments Laboratory
GSFC/Detector Systems Branch
GSFC/Detector Systems Branch
GSFC/Detector Systems Branch
GSFC/Detector Systems Branch
GSFC/Materials Engineering Branch
GSFC/Materials Engineering Branch
GSFC/Materials Engineering Branch
ARC/Nanotechnology Branch
GSFC/Catholic University of America
GSFC/Catholic University of America
GSFC/Catholic University of America
ESMD Summer Internship Program
•
•
•
Prof. David Allred
Prof. Richard Vanfleet
Johnathan Goodsell
Brigham Young University/Dept. of Physics & Astronomy
Brigham Young University/Dept. of Physics & Astronomy
Brigham Young University/Mechanical Engineering Dept.
•
Jonathon Brame
Brigham Young University/Dept. of Physics & Astronomy
MUCERPI Summer Internship Program
•
Melissa Harrison
Fisk University
This work was supported by the Goddard Space Flight Center Director’s Discretionary Fund, the GSFC IRAD Program,
the Minority University College Education and Research Partnership Initiative, and the
Exploration Systems Mission Directorate Faculty-Student Summer Internship Program
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Extra Slides
March 19, 2007
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Nanoelectronic Materials
Courtesy Fuhrer Group, Univ Maryland, College Park
Single-walled Carbon Nanotubes
• Characterized by chirality,
diameter
– Diameter ~ 1 nm
Metallic SWCNT:
• Metallic or Semiconducting
n – m = 3 x integer
– Difficult to control  trend toward
SWCNT network devices
• Electronic properties sensitive
to deformation
– Strain sensing
March 19, 2007
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Courtesy Smalley Group, Rice Univ.
NASA Headquarters
Nanoelectronic Materials, Cont.
Multi-walled Carbon Nanotubes
• Exclusively metallic
– Similar to graphite
• Diameters 30-100 nm
– Larger than SWCNTs
• High aspect ratio with many
available electrons
– Field emission
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E-gun for MEMS Time-of-Flight
Mass Spectrometer :
Planetary Atmospheric Science
and biologically significant
molecular species for astrobiology
Ion lens assembly
prototype
Carbon Nanotubebased Electron Gun
March 19, 2007
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Field Emission
Comparison: Candidate Technologies
Type
CNT Field
Emitter
Spindt
Emitter
Thermionic
Emitter
1010 /cm2*
5x107 /cm2†
1 /cm2
Current @
Voltage
100μA @ 50V**
1mA @
150 V*
Operating
Temp
Ambient
Ambient
>700°C¶
Redundancy
(2mm diam)
3x108
106
1
Metric
MWCNTs
Spindt
Emitters
Thermionic
Density
*This work
**Optimized
†V. M. Aguero and R. C. Adamo, 6th Spacecraft Charging Technology
Conference (2000).
¶Barium Oxide-coated Tungsten
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Field Emission
Patterned CNT Cathode
• CNT tower
dimensions
– 5 μm x 5 μm x
10 μm (height)
• 50 μm pitch
• 2mm x 2mm
array
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Field Emission
Patterned MWCNTs for High
Performance E-gun
Electric Field (V/m)
4 10
-5
3.2 10
-5
2.4 10
-5
1.6 10
-5
8 10
-6
0.2
0.4
0.6
0.8
1
Fit to Fowler-Nordheim Tunneling:
2
J = K E exp(-K /E)
1
2
1.2
1.4
1.6
-11
1.2 10
-25
1 10
-11
-26
-27
8 10
-12
6 10
-12
4 10
-12
2 10
-12
-28
2
-8 10
0
ln(J/E )
-Emission Current (A)
-5
-29
0.6
0.7
0.8
0.9
1/E
1
1.1
-30
1.2
0
0
-6
-2 10
0
50
100
150
200
-12
-Emission Current Density (A/um2)
4.8 10
GSFC patterned
MWCNT emitter:
• Cathode-grid
spacing = 140 µm
• Turn-on voltage
<100 V
• 50 µA @ 10 mW
Compare to CassiniHuygens thermionic
e-gun:
• 80 µA @ 1000 mW
Extraction Voltage (V; grid bias)
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Field Emission
Turn-on Voltage (V)
Sample Database
3.5 10
2
3.0 10
2
2.5 10
2
2.0 10
2
1.5 10
2
1.0 10
2
Turn-on voltage versus Cathode-Grid Spacing
350
 Best performer:
– GSFC patterned
sample
– 50 uA @ gap =
140 um
ARC1
300
250
GSFC060802-2
200
150
ARC2-21
50
100
50
ARC2-11
GSFC:EGp2
0.0
0
ARC2-22
GSFC060803-1
-50
-20
0
20
40
60
GSFCpattern-1
80
100
Cathode-Grid Spacing (um)
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120
-50
140
Field Emission
Side-by-Side E-Gun Evaluation
Thermionic e-gun
CNT e-gun
lens
stack
filament
repeller
Recent and Upcoming Work:
Compare candidate e-gun technologies, fully integrated with aperture/lens stack
Towards Integration into MEMS Time-of-Flight Mass Spectrometer
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Future Work for Summer Interns: CNT E-Gun
• Lifetime testing of CNT emitters
• Study of performance in ambient gas
environment
• Maturation of fabrication techniques
• Maturation of packaging techniques
• Advanced electronics to develop
feedback/ballast for current stabilization
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