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Materials Science Research: Testing and Manufacturing in Space

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Presented at the 2015 International Space Station Research and Development Conference.

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Materials Science Research: Testing and Manufacturing in Space

  1. 1. Materials Science Research: CARL KIRKCONNELL, PRESIDENT, WEST COAST SOLUTIONS JUD READY, DEPUTY DIRECTOR, GEORGIA TECH INSTITUTE FOR MATERIALS ALEKSANDER OSTROGORSKY, PROFESSOR, ILLINOIS INSTITUTE OF TECHNOLOGY ALEXEI CHURILOV, SENIOR SCIENTIST, RADIATION MONITORING DEVICES, INC. Testing and Manufacturing in Space
  2. 2. W. Jud Ready DEPUTY DIRECTOR, INNOVATION INITIATIVES
  3. 3. LIGHT TRAPPING 3D PHOTOVOLTAICS Solves “thick-thin” conundrum Light Trapping = more absorbance Thinner layers = less recombination Traditional planar photovoltaics allow for only a single impingement of the photon, limiting absorption. Anti‐reflection (AR) coatings can improve upon this deficiency, but only to a limited extent due to wave‐length dependency of the AR coating. The CNT‐based textured device permits multiple impingements of a single photon significantly increasing absorption probability.
  4. 4. When choosing a photovoltaic material, several idealities are understood: 1. Robust p-type or n-type conductivity 2. Strong optical absorption coefficient 3. Direct bandgap of ~1.5 eV 4. Low-cost, abundant, non-toxic chemical elements 5. Low-cost material fabrication and growth 6. Compatible with a variety of technologies, structures, and applications Cu2ZnSnS4 (CZTS) posses all of these qualities! A quaternary semiconductor compound belonging to a class of materials known as chalcogenides CZTS is fundamentally similar to CuInxGa1-xSe2 (CIGS) THIN FILMS - CZTS
  5. 5. Copper-zinc-tin-sulfide (CZTS) thin-films are next-generation solar cells comprised of cheap, Earth-abundant materials - High absorption coefficient (>104 cm-1)—ideal for thin film purposes - Direct energy band-gap implies resistance to radiation - 1.5 eV band-gap—highest solar conversion efficiency based on Shockley- Queisser Limit CZTS PHOTOVOLTAICS
  6. 6. 1 in. 3-D CZTS CELL STRUCTURE
  7. 7. FLIGHT HARDWARE 20 PV cells in both 3D and planar configurations will be launched via SpaceX September 9, 2015 to be tested outside the International Space Station (ISS). The samples will be returned to Earth to be investigated for radiation and physical damage after 6 month external exposure. 4U cubesat With 20 PV cells
  8. 8. Cubesat is passed outside ISS via JEM air lock CZTS TESTING IN SPACE ENVIRONMENT
  9. 9. 1. J. Flicker and W. J. Ready, “Derivation of Power Gain for Three Types of Three Dimensional Photovoltaics Cells Based on Tower Arrays with Flat Tops and Smooth, Vertical Sidewalls.” Progress in Photovoltaics: Research and Applications. Vol. 19, pp. 667-675 (2011). 2. X.J. Wang, J.D. Flicker, B.J. Lee, W.J. Ready and Z.M. Zhang, “Visible and Near- infrared Radiative Properties of Vertically Aligned Multi-walled Carbon Nanotubes.” Nanotechnology, Vol. 20 pp. 215704-215713, (2009). 3. Jack Flicker and Jud Ready, “Simulations of Absorbance Efficiency and Power Production of Three Dimensional Tower Arrays for Use in Photovoltaics.” Journal of Applied Physics, Vol. 103, pp. 113110 (2008). 4. S.P. Turano, J.D. Flicker; W.J. Ready, “Nanoscale Coaxial Cables Produced From Vertically Aligned Carbon Nanotube Arrays Grown via Chemical Vapor Deposition and Coated with Indium Tin Oxide via Ion Assisted Deposition.” Carbon, Vol. 46, No. 5, pp. 723-728, (2008). 5. US Patent #8,350,146 -- Three Dimensional Multi-junction Photovoltaic Device (January 2013). REFERENCES
  10. 10. ACKNOWLEDGEMENTS
  11. 11. GTRI_B-‹#› Questions? W. Jud Ready jud.ready@gatech.edu 404-407-6036
  12. 12. DETACHED MELT AND VAPOR GROWTH OF InI IN SUBSA HARDWARE Prof. Aleksandar Ostrogorsky, PI, IIT Dr. Alexei V. Churilov, RMD Watertown, MA Dr. Martin P. Volz NASA MSFC, Huntsville, AL Dr. Lodewijk van den Berg, Constellation Technology Largo F Prof. Dr. Arne Cröll University of Freiburg, Germany. SUBSA “1” (1995-2004) Te and Zn doped InSb “2” (2015->2017) InI
  13. 13. SAMPLE HEADER • SCR 1998 • Design review 2000 • Endeavour, Expedition 5, 2002. • Seven Te- and Zn-doped InSb (MP 512 C) semiconductor crystals were grown. SUBSA 2002 in MSG W. Bonner
  14. 14. SAMPLE AMPOULE ASSEMBLY (SAA)
  15. 15. SUBSA AMPOULE ASSEMBLY Length = 30 cm The Piston-Spring Support Quartz plug InSb Graphite Baffle Spring 16 mm O.D. I.D. = 12.0 mm •InSb seed •50g InSb, doped with Te or Zn (MP 512 C) •Sealed under vacuum. Bill Bonner
  16. 16. SUBSA HARDWARE AT AT GLANCE 1 Process Control Module 1 DaqPad Video Camera LabVIEW 6i processes data on MSG Laptop Computer Cartridge head and 4 TCs
  17. 17. SUBSA DESIGN REWIEW 6/8/2000
  18. 18. SUBSA STATUS ON SUNDAY 2/3/2002 FedEx Custom Critical “White Gloves” service departing MSFC’s Microgravity Development Lab at approximately 3:30 PM CST on Sunday 2-3-2002. The SUBSA-PFMI flight hardware & software arrived at KSC on Monday morning, February 4, 2002, in good condition. Photo by Tec-Masters / Reggie Spivey February 3, 2002
  19. 19. CREW OF THE EXPEDITION FIVE June 5, 2002. Shuttle Endeavour, Flight UF-2 -STS-111 Valery Korzun Expedition commander Sergei Treschev flight engineer
  20. 20. REAL TIME VIDEO – CONTROL OF SEEDING AND GROWTH RATE Solid/Liquid Interface Seed Interface Solid/Liquid Interface Precise seeding Monitoring room at RPI Dr. Whitson July 11, 2002 f = 0.5 cm/hr
  21. 21. Results SUBSA #10: Zn-doped 0 1 2 3 4 5 6 7 8 9 10 0 5 10 15 20 25 30 35 x [mm] SIMS_1 SIMS_2 Smith_Co=3.5e18 18 3 10Zn cm     D-shaped section with attached seed de-wettingSeed D =1.2 x 10-4 cm2/s SUBSA 10: Zn-doped; with baffle Zn-doped => k0=2.9 k0 >1 is proffered for growth in microgravity.
  22. 22. SUBSA RESULTS: 1. Demonstrated reproducible diffusion-controlled “segregation” 2. Diffusion coefficients for Te and Zn in InSb 3. Segregation theory: BPS (1953) Ostrogorsky and Muller (1992) Ostrogorsky (2012): CZ, Bridgman, ZM.. keff = CS CL = F k0 ,D, fdSF( ) k0 is equilibrium segregation coefficient f [cm/s] is freezing rate D[cm2/s] diffusion coefficient. “stagnant film” thickness dFC =1.61D1/3 n1/6 w-1/2 keff = F k0 ,Pe,Re,Gr,Pr,Sc,( ) ω =crystal rotation rate Steady laminar flow ! g =? GrL = gb DT L3 n2 Witt et al. J.Electrochem Soc.125 (1978) Chapter 25, Handbook of Crystal Growth, 2nd ed.
  23. 23. SUBSA RESULTS: SEGREGATION THEORY FOR ZONE REFINING Pfann’s book: Zone Refining”, 1966. Ostrogorsky and Glicksman, “Handbook of Crystal Growth”, 2014. d = ? fd D = ? keff = F k0 ,Pe,Re,Gr,Pr,Sc,( )
  24. 24. Why semiconductor ? Why InI ? • High spectroscopic resolution: to identify special nuclear materials • Hand-held, RT battery operation 0 2% 7 % 4% 6% 3LaBr NaI CZTGe Limit of semiconductors 0.2 % Limit of scintilators 2 % 2HgI 1% • 1.5<Eg< 2.5 eV, to minimize the leakage current • High density • One of the elements should have Z>50 • Acceptable mechanical properties, for device fabrication and use. InI Eg=2 eV ρ=5.6 g/cm3 Z=53
  25. 25. REQUIREMENTS FOR RT DETECTORS Room Temperature (RT) operation requirements energy gap: 1.5 eV< Eg <2.5 eV Z>50 II III IV V VI Best Z [eV] Si 14 1.12 Ge 32 0.7 GaAs 33 1.43 InP 49 1.35 AlSb 51 1.6 CdTe 52 1.49 ZnTe 52 2.25 HgI2 80 2.13 HgBr 2 80 3.6 PbI2 82 2.55 BiI3 83 1.75 TIBr 81 2.8 TlI 81 2.15 Cd0.8Zn0.2Te “CZT” III-V compounds
  26. 26. Structure, hardness, Z, Eg, mobility Structure Knoop kg/mm2 Ρ [g/cm3] Z Eg μe μh Comments III-V AlSb 460 4.22 31/51 1200 700 good/difficult GaAs Zincblende 450 5.34 31/33 1.42 8000 400 low Z and Eg InP Zincblende 400 4.79 49/15 1.35 4600 150 low Z and Eg II-VI CdTe Zincblende 45 - 60 6.2 48/52 1.52 1000 80 good/difficult ZnTe Zincblende 92 6.0 30/52 2.25 good/difficult GaSe Se-Ga-Ga-Se 4.55 31/34 2.02 215 van der Waals CdSe Wurtzite 90-130 5.8 48/34 1.73 720 75 CdS Wurtzite-cubic 18 4.82 48/16 2.42 75 75 Layered HgI2 α-tetragonal 10 6.36 80/53 2.13 100 4 van der Waals PbI2 rombohedral 10 6.16 82/53 2.35 8 2 van der Waals BiI3 rombohedral 10 5.78 83/53 1.73 van der Waals iodides InI orthorhombic 27 5.39 49/53 2.0 22 NOT TOXIC TlI Orthorhombic 18 7.29 81/53 2.15 transformation bromides TlBr cubic 12 7.56 81/35 2.68 7 2 toxic TlBrI orthorhombic 27 81/53/35
  27. 27. WHY INDIUM IODIDE? 2727 15 mm diameter • Promising semiconductor RT detector material + not toxic; MP= 360 C (perfect for SUBSA furnace) • Developed procedures for synthesis, ZR, melt growth, vapor growth • RPI (2006-2009); IIT (2009-present), RMD (2015). • DoE, NNSA
  28. 28. CZOCHRALSKI GROWTH OF InI • Detector materials have high vapor pressure; growth in sealed ampoules. • CZ growth of a detector crystal demonstrated for the first time
  29. 29. DISTRIBUTION OF PRECIPITATES CZOCHRALSKI BRIDGMAN 0 3 6 9 12 15 18 21 24 27 104 105 106 Density of precipitates in InI CZ01 Volume: 800x800x100 m3 Black - last to freeze Red - first to freeze Density(cm-3 ) diameter (m) 0 3 6 9 12 15 18 21 24 104 105 106 Density of precipitates in InI Bridgman Volume: 800x800x100 m3 Black - last to freeze Red - first to freeze diameter (m) Density(cm-3 )
  30. 30. PURIFICATION BY ZONE REFINING (ZR) 100 g ingot, after 70 ZR passes IIT 2012 350 g ingot, was ZR and grown in an open boat, under dynamic gas flow 5% H2 +95 %Argon, RMD 2015. RMD 2015 IR-light No inclusions (?)
  31. 31. Inclusions in InI and CdTe RMD 2015 IR-light No inclusions (?) IR-TRANSMISSION IMAGES • InI sample originating from InI-ZR-05 experiment has no inclusions • CdTe sample with inclusions
  32. 32. Crystal Growth of Cs2LiYCl6:Ce in Microgravity ALEXEI CHURILOV, SENIOR SCIENTIST, RADIATION MONITORING DEVICES, INC. ALEKSANDAR OSTROGORSKY, PROFESSOR, ILLINOIS INSTITUTE OF TECHNOLOGY JOSHUA TOWER, SENIOR SCIENTIST, RADIATION MONITORING DEVICES, INC. MARTIN VOLZ, MATERIALS SCIENTIST, NASA MARSHALL SPACE FLIGHT CENTER
  33. 33. CLYC (Cs2LiYCl6:Ce) CLYC is the first commercial dual-mode scintillator: gamma-ray spectroscopy AND neutron detection Fast, accurate isotope identification CLYC crystals CLYC instruments RadEye RIIDEye 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 1 2 3 AmBe spectrum 137 Cs spectrum 662 keV 3.4 MeV intensity,arb.units energy, MeV ~ 3.8% FWHM Gamma rays ~ 2.5% FWHM neutrons
  34. 34. CLYC FEATURES • Bright response and high efficiency for neutrons • 1 cm of 95% 6Li enriched CLYC  ~80% efficiency for thermal neutron detection • Pulse shape discrimination (PSD) for gamma- rays and neutrons • Rise & decay times different for n and γ (PSD) • Good proportionality  gamma-ray energy resolution • 25-30% better than NaI(Tl), FWHM ~ 4% @ 662 keV • Fast neutron detection due to presence of 35Cl
  35. 35. CLYC PULSE SHAPE DISCRIMINATION Ability to differentiate between gamma rays and neutrons based on pulse shapes 0 200 400 600 0.0 0.2 0.4 0.6 0.8 1.0 1.2 gamma neutron window 2window 1 neutron gamma windows counts,arb.units time, ns Neutrons Gamma Rays Neutrons Gamma Rays Thermal neutrons
  36. 36. FAST NEUTRON DETECTION WITH CLYC 0 1 2 3 4 5 6 En =thermal CLYC:Ce 1.1 MeV 1.6 MeV 2.3 MeV intensity,arb.units CP energy, MeV 3.9 2.9 2.1 35Cl + 1n  1p + 35S + energy 0.5 1.0 1.5 2.0 2.5 3.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 35 Cl CPenergy,MeV neutron energy, MeV Proportional to 1n energy
  37. 37. DEFECTS IN CLYC Grain Boundaries Inclusions Cracks Growth in microgravity to address defect formation mechanisms
  38. 38. • Absence of density-driven segregation of components  Eliminated effect of density differences between CLYC components (CsCl, LiCl, YCl3) → more uniform initial melt composition • Absence of thermal buoyancy-driven convection in the melt  More axially homogeneous composition of CLYC components in crystals • Weightlessness of the melt volume  Melt confined by surface tension → Reduced cracking Key advantages of microgravity for crystal growth research:
  39. 39. TECHNICAL APPROACH • Utilize existing SUBSA hardware: furnace, ampoules, glovebox • Conduct a series of tests in identical ground-based hardware • Optimize SUBSA growth ampoules for CLYC • Grow 4 CLYC crystals on ISS with varied parameters:  Ampoule geometry  Temperature setpoint  Nucleation method (seeded and self-nucleated)  Detached and confined melt • Do a set of reference ground-based experiments under the same thermal conditions as in space. • Characterize and compare crystals grown in space and on the ground. SUBSA ampoule. Cs2LiYCl6:Ce will be used in place of InSb charge and seed. Four external thermocouples will be attached to the ampoule for temperature monitoring. Length = 300 mm OD = 16 mm Internal atmosphere: vacuum 10-6 Torr.
  40. 40. SUBSA HARDWARE Image from camera
  41. 41. SUMMARY • RMD, Inc. developed and commercialized Cs2LYCl6:Ce – the first scintillator crystal used for detection of both gamma- rays and neutrons. • Four CLYC crystals to be grown on ISS. • Goals:  Understand mechanisms of defects formation in CLYC crystal growth without interference of gravity.  Focus on optimization of parameters with the largest impact on quality and yield, for improved production on Earth. Integrated on PMT Packaged ø2”x2” CLYC crystal 0 200 400 600 800 0.0 0.5 1.0 E = 24eV or 3.6% 662 keV intensity,counts/sec energy, keV

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