SOLIDIFICATION USING A BAFFLE IN SEALED AMPOULES (SUBSA)
Research Area: Materials Science
Expedition(s): 5
Principal Investigator(s): ● Aleksander G. Ostrogorsky, PhD, Rensselaer Polytechnic
Institute, Troy, New York
RESEARCH OBJECTIVES
Solidification Using a Baffle in Sealed Ampoules (SUBSA) provides experimental methods of
crystallizing melts in microgravity are expected to result in reduced fluid motion in the melt,
leading to better distribution of subcomponents and the potential for improved technology
used in producing semiconductor crystals.
EARTH BENEFITS
Semiconductor materials can conduct, stop or modify a wide range of electrical and optical
signals. Therefore, all computer chips, sensors, and wireless communication devices, etc. are
built from tiny chips cut from large semiconductor crystals. Improved semiconductor quality,
well-formed crystals with few or no imperfections, are the key reason that the electronic
devices today are so much smaller and more powerful than their predecessors.
SPACE BENEFITS
The SUBSA furnace, with its
capability to control and visualize
melting and solidification of
semiconductor crystals, has
increased our understanding of
solidification phenomena. The
transparent furnace coupled
with the video downlink and
real-time commanding capability
provides a powerful tool for
scientists and engineers. The
scientists were able to watch the
motion of the crystal-melt
interface as semiconductor
crystals were formed. The design
of the SUBSA ampoule that
includes a baffle and a system
that prevents de-wetting resulted
in crystals whose properties have
not been disrupted by micro-
accelerations at the Station, making it possible for future researchers to produce the high-
quality semiconductor crystals that are in demand on Earth.
One of the first materials science experiments on the International
Space Station - the Solidification Using a Baffle in Sealed Ampoules
(SUBSA)—will be conducted during Expedition 5 inside the
Microgravity Science Glovebox. Dr. Aleksandar Ostrogorsky, a
materials scientist from the Rensselaer Polytechnic Institute, Troy,
NY, and the principal investigator for the SUBSA experiment, uses the
gloves to examine an ampoule like the ones used for his experiment
inside the glovebox's work area. The Microgravity Science Glovebox
and the SUBSA experiment are managed by NASA's Marshall Space
Flight Center in Huntsville, Alabama. NASA/MSFC image.