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Fabrication and Testing of a Strain-Based Carbon Nanotube Magnetometer Structure

Fabrication and Testing of a Strain-Based Carbon Nanotube Magnetometer Structure. Jon A. Brame, Johnathan Goodsell, Stephanie A. Getty ¹ , Y. Zheng ¹ And David A. Allred Brigham Young University ¹ NASA GSFC Code 541 Began as an NASA ESMD Student-Faculty Program. Overview.

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Fabrication and Testing of a Strain-Based Carbon Nanotube Magnetometer Structure

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  1. Fabrication and Testing of a Strain-Based Carbon Nanotube Magnetometer Structure Jon A. Brame, Johnathan Goodsell, Stephanie A. Getty¹, Y. Zheng¹ And David A. Allred Brigham Young University ¹NASA GSFC Code 541 Began as an NASA ESMD Student-Faculty Program Jon Brame

  2. Overview • Project Motivation and Goal • Fabrication Process • Outcomes Jon Brame

  3. CNT Properties • Change in Conductivity with Strain • Tombler, et al (Nature, 2000) • Single tube Jon Brame

  4. CNT Properties • Change in Conductivity with Strain • Tombler, et al (Nature, 2000) • Single tube Jon Brame

  5. Motivation • Space Magnetometry • Spacecraft Orientation • Magnetic Field Studies • Planetary Exploration • Astronaut/Rover Orientation • Planetary Geology Jon Brame

  6. Device Operation Jon Brame

  7. Needle Gold Si02 Si Jon Brame

  8. Prototype Jon Brame

  9. Vacuum Chamber for Thin Film Deposition Process: Catalyst • Indirect Iron Catalyst Deposition Jon Brame

  10. CVD Growth Furnace Diagram of CVD Growth Process SEM Image of SWCNT Mat Process: SWCNT Growth • Chemical Vapor Deposition (CVD) SWCNT Growth Jon Brame

  11. Process – Electrical Contact • Gold Contact Pads • Detector Development Lab (DDL) • E-Beam Lithography • Deposition: Chrome(100Å)-Gold(1000Å) • Lift-off Jon Brame

  12. Diagram of SWCNT network, contact pads and iron needle Process – Iron Needle • Iron Needle • Device Alignment • E-Beam Lithography pattern • Deposition: Chrome-Iron-Chrome • Lift-off Jon Brame

  13. Au SWCNTs Remnant needle Au Diagram of completed device Process – Trench • Lithography (manual) • Etching • Buffered Oxide Etch • KOH Trench Jon Brame

  14. Successfully etched trench with SWCNT spanning gap between gold electrodes Results • Completed Magnetometer Prototype Jon Brame

  15. Results • Magnetic Field Measurement Testing Jon Brame

  16. Micrograph of Test Structure Jon Brame

  17. Jon Brame

  18. alignment mark SWCNT mat Gold pad Iron needle “Rolled-up” SWCNT mat Trench Jon Brame

  19. 500 seconds into the experiment the field is ramped down(b) b a c Device resistance decreases as magnetic field is increased, Experimental Results • At some point contact with one of the pads becomes intermittent leading to the noisy signal during time period c Note: Behavior during a & b are theopposite of what was expected to happen. Jon Brame

  20. CONCLUSIONS • A fabrication process for magnetometer test structures has been demonstrated. • An array of prototype magnetometer test structures has been successfully fabricated. • The test structures consist of a high aspect-ratio iron needle suspended above a trench by a mat of SWCNT. Gold pads electrically contact the SWCNT mat. This fabrication process is now available and being used in various field sensing applications. • Initial magnetic testing indicates that there is some correlation between magnetic field and measured resistance in the device. • Further device fabrication and testing is necessary to establish the extent of this relationship. Jon Brame

  21. a b c a b c The design for the next iteration of gold-pad geometry features three separate sets of pads (labeled a, b & c) to contact specific sections of nanotubes. In this figure the black Xs represents the nanotube mat and the horizontal line is the needle. Dividing the pads into three sets makes it possible to uses the outer set of pads (labeled a & c) to measure the strain across the outer portions of the nanotubes. Jon Brame

  22. Acknowledgements Bryan Hicks, Rachel Bis, Melissa Harrison • Branch 541: Dewey Dove, D. Stewart Bruno Munoz, Carl Taylor, Len Wang, D. Rowland • BYU: Prof. Richard Vanfleet, Dr. Jeffrey Farrer, Prof. Robert Davis, David Hutchinson • Other: Lynda Goodsell, Bill Heaps • Division 540; Dick Fahey; Joshua Halpern; ESMD; Rocky Mountain Space Grant Consortium Jon Brame

  23. We gratefully acknowledge financial support from NASA GSFC Director’s Discretionary Fund, the NASA Internal Research and Development Fund , the Rocky Mountain Space Grant Consortium , and the Student/Faculty Internship Program for the summers of 2006 and 2007 which provided support for J. A. Brame, J. E. Goodsell, & D. D. Allred Jon Brame

  24. Outcome: BYU Collaboration Jon Brame

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