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Morphological Stability of Faceted InterfacesThe major focus of this investigation is to study the fundamentals of layer spreading mechanisms during growth of doped Ge (a facet forming material), and to determine the conditions for morphological instability of vicinal solid-liquid interfaces. The investigation will also lead to the determination of the effect of dopants on the layer growth kinetics, step free energy, and dopant capture by the advancing ledges. The theoretical treatment of growth of faceted interfaces indicates that the kinetics of a step on a growing vicinal interface considerably depends on its angle of inclination, the melt concentration, and characteristics of flow currents in the melt. The morphological stability of the interface also depends on these parameters, as well as on the density and spreading velocity of the steps. However, the treatment of the instability of the interface by the layer growth mechanism is rather difficult because it requires exact knowledge of the thermal and solutal fields, hydrodynamics of the melt, and supercooling at the interface. The results of recent space experiments of the principal investigator involving directional solidification of faceted Bi-Sn alloys have shown that the morphological stability of various crystallographic orientations is significantly affected by the anistropy in interfacial properties of the faceted alloy in general, and the interface kinetics in particular. These findings have also raised many important and fundamental questions, particularly with respect to the behavior of interfacial steps, which need to be addressed via additional groundbased and microgravity experiments. For the present investigation we will use a novel crystal growth technique which provides axial heat flux close to the solid-liquid boundary. The Axial Heat Processing (AHP) technique allows for precise control and determination of the heat and mass transfer close to the crystallization front, and the establishment of a planar interface over the entire cross-section of the growing crystal.
Document ID
20010057201
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Abbaschian, Reza
(Florida Univ. Gainesville, FL United States)
Golyshev, V. D.
(Center of Thermophysical Research Russia)
Gonik, M.
(Center of Thermophysical Research Russia)
Tsvetivsky, V.
(Center of Thermophysical Research Russia)
deVahlDavis, G.
(New South Wales Univ. Sydney, Australia)
Leonardi, E.
(New South Wales Univ. Sydney, Australia)
Date Acquired
August 20, 2013
Publication Date
March 1, 2001
Publication Information
Publication: Microgravity Materials Science Conference 2000
Volume: 1
Subject Category
Solid-State Physics
Funding Number(s)
CONTRACT_GRANT: NAG8-1673
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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