Synthesizing Semiconductor and Scintillator Crystals in Space

Last week, crew members set up and calibrated the refurbished Solidification Using a Baffle in Sealed Ampoules (SUBSA) hardware onboard the International Space Station National Lab and began processing samples. SUBSA is a high-temperature furnace that can be used to study how microgravityThe condition of perceived weightlessness created when an object is in free fall, for example when an object is in orbital motion. Microgravity alters many observable phenomena within the physical and life sciences, allowing scientists to study things in ways not possible on Earth. The International Space Station provides access to a persistent microgravity environment. affects the synthesis of semiconductor and scintillator crystals. Such crystals can be used to detect radiation and have important applications in homeland security and defense devices.

Production of semiconductors and scintillators involves combining and melting various elements that crystallize as they cool. On Earth, gravity-driven convection during synthesis can lead to semiconductor and scintillator crystals with imperfections such as cracks and bubbles that affect the performance of the crystals. In microgravity, however, convection is minimized, enabling the synthesis of higher quality crystals with fewer imperfections—which could ultimately lead to improved functionality of semiconductors and scintillators back on the ground. SUBSA is equipped with high-definition video imaging that allows investigators to monitor samples and observe the melting and crystallization processes in real time.

The original SUBSA hardware launched to the ISSInternational Space Station in 2002 and was returned to Earth shortly after the completion of initial experiments. Following a growing demand on the ISS National Lab for capabilities provided by SUBSA, NASANational Aeronautics and Space Administration agreed to refurbish the hardware and worked together with the ISS National Lab to select payloads to utilize the renovated furnace.

Learn more about SUBSA and some of the ISS National Lab investigations using the upgraded hardware to improve synthesis of semiconductor and scintillator crystals in the Upward feature “The Little Furnace that Could: Using Space to Improve Radiation Detection.”