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Comparison of OARE Accelerometer Data with Dopant Distribution in Se-Doped GaAs Crystals Grown During USML-1Experiments were conducted in the crystal growth furnace (CGF) during the first United States Microgravity Laboratory (USML-1), the STS-50 flight of the Space Shuttle Columbia, to determine the segregation behavior of selenium in bulk GaAs in a microgravity environment. After the flight, the selenium-doped GaAs crystals were sectioned, polished, and analyzed to determine the free carrier concentration as a function of position, One of the two crystals initially exhibited an axial concentration profile indicative of diffusion controlled growth, but this profile then changed to that predicted for a complete mixing type growth. An analytical model, proposed by Naumann [R.J. Naumann, J. Crystal Growth 142 (1994) 253], was utilized to predict the maximum allowable microgravity disturbances transverse to the growth direction during the two different translation rates used for each of the experiments. The predicted allowable acceleration levels were 4.86 microgram for the 2.5 micrometers/s furnace translation rate and 38.9 microgram for the 5.0 micrometers/s rate. These predicted values were compared to the Orbital Acceleration Research Experiment (OARE) accelerometer data recorded during the crystal growth periods for these experiments. Based on the analysis of the OARE acceleration data and utilizing the predictions from the analytical model, it is concluded that the change in segregation behavior was not caused by any acceleration events in the microgravity environment.
Document ID
20000053504
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Moskowitz, Milton E.
(Case Western Reserve Univ. Cleveland, OH United States)
Bly, Jennifer M.
(Case Western Reserve Univ. Cleveland, OH United States)
Matthiesen, David H.
(Case Western Reserve Univ. Cleveland, OH United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1997
Publication Information
Publication: Journal of Crystal Growth
Publisher: Elsevier
Volume: 174
ISSN: 0022-0248
Subject Category
Solid-State Physics
Funding Number(s)
CONTRACT_GRANT: NAS8-39722
Distribution Limits
Public
Copyright
Other

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