Detached Melt and Vapor Growth of InI in SUBSA Hardware (Detached Melt and Vapor Growth of InI) - 01.24.18
In previous research, Indium iodide (InI) showed promise as a material for detecting nuclear radiation at room temperature. As a non-toxic, stable material with a relatively low melting point, it also is ideal for experiments aboard the space station. The Detached Melt and Vapor Growth of InI in SUBSA Hardware (Detached Melt and Vapor Growth of InI) investigation grows separate, high-quality InI crystals in microgravity in order to test it against more expensive and difficult-to-grow current detection materials such as Cadmium Zinc Telluride (CZT). This work advances the process of fabricating high-quality InI and other crystals on Earth for use as better and less expensive detectors of nuclear radiation. Science Results for Everyone
Information Pending
OpNom:
Principal Investigator(s)
Aleksander Ostrogorsky, Sc.D., Illinois Institute of Technology, Chicago, IL, United States
Co-Investigator(s)/Collaborator(s)
Information Pending
Developer(s)
Illinois Institute of Technology, Chicago, IL, United States
NASA Marshall Space Flight Center, Huntsville, AL, United States
Tec-Masters Inc., AL, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
Sponsoring Organization
National Laboratory (NL)
Research Benefits
Earth Benefits, Scientific Discovery
ISS Expedition Duration
September 2016
- September 2017
Expeditions Assigned
49/50,51/52
Previous Missions
SUBSA initially launched on STS-111, ISS Flight UF2 in 2002. All hardware was returned on STS-113, ISS Flight 11A in 2002 and STS-114, ISS Flight LF-1.1 in 2005.
Experiment Description
Research Overview
- Verify that the SUBSA furnace is ideal for growing reference quality crystals, having higher crystalline and chemical perfection than the crystals grown on earth. This is especially true for simple congruently melting and/or evaporating materials.
- Study the de-wetting and detached growth in the SUBSA furnace in the Microgravity Science Glovebox (MSG) on the ISS can help in the development of equipment for detached growth on Earth.
Description
- Its energy gap Eg=2.0 eV is above that of CZT, hence less leakage current.
- Its density (5.31 g/cm3) is sufficiently high, although lower than density of CZT (5.78 g/cm3).
- It is not toxic; it is not hydroscopic.
- It is easy to grow from the melt since there are no problems related to compositional segregation, phase separation, volatility of Cadmium, Zinc and Tellurium. Post growth annealing is not needed.
- Minimize the number of defects in InI crystals.
- Determine the nature of the defects.
- Produce reference quality InI (highest achievable crystalline and chemical perfection), in order to determine if such crystals can compete with CZT.
- To determine if InI can compete with CZT as a room temperature detector material.
- Detached melt growth of InI in microgravity.
- Physical vapor transport growth of InI under diffusion controlled vapor transport conditions. Since InI evaporates congruently (vapor consist of InI molecules) the process is extremely simple. Molecules of InI sublime from a high purity solid source at the hot end of an evacuated ampoule, travel as vapor, and crystalize at the cold end of the ampoule. Diffusion transport (with no convection) is expected to increase crystalline perfection and reduce the concentration of impurities in the growing crystal.
- Electrical resistivity to well above 5x1011 ohm-cm. Potential benefits are low leakage current. Note that resistivity of CZT is ~ 3x1010 Ohm-cm
- Mobility-lifetime (μτ) product approaching that of CZT ( for electrons (μτ)e> 3 x10-3 cm2/V and for holes (μτ)h> 5 x10-5 cm2/V.
- Detector energy resolution approaching 2% FWHM at 662 keV.
- Four InI crystals, by detached directional solidification. The growth rate will be 2 mm/hr. Each melt-growth experiment is expected to last ~ 24 hrs. The ampoules are produced at the Illinois Institute of Technology (IIT), by the PI and his student V. Riabov.
- Two crystals are grown using physical vapor transport growth. As a rule, vapor-growth experiments conducted in microgravity are not affected by convection, and have produced crystals with superior properties. The experiments are expected to last 2 to 4 weeks, depending on the time available. The ampoules for vapor growth are produced at the Marshall Space Flight Center (MSFC) by M. Volz and A. Croell (international co-investigator, University of Freiburg, visiting MSFC and the University of Alabama at Huntsville). Dr. Lodewijk van den Berg, Constellation Technologies, is the consultant for vapor growth.
Applications
Space Applications
Information Pending
Earth Applications
Inexpensive InI-based detectors capable of operating at room temperature have many potential applications, including as medical sensors, in security inspections, for detection and evaluation of nuclear emergencies and detection of hard X- and γ-rays for astrophysical studies, and for surveillance of nuclear activity.
Operations
Operational Requirements and Protocols
- Activate the Microgravity Science Glovebox (MSG).
- Load a sample into the SUBSA furnace.
- Establish processing conditions per Glovebox Investigator (GI) and safety requirements.
- Request the recording of microgravity measurement data from the sensor in the MSG.
- Ensure that commanding and data and video downlink is enabled for the required time periods.
- Melt and re-solidify the sample or grow a sample from vapor transport.
- Remove the sample and store.
- Downlink SUBSA data and video not downlinked during the experiment.
Decadal Survey Recommendations
CategoryReference
Applied Physical Science in Space
AP9
Applied Physical Science in Space
AP10
Results/More Information
Information Pending
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