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Crystal-melt interface shape of Czochralski-grown large diameter germanium crystalsCrystal-melt interface shapes of 100 to 200 mm diameter 111-line Ge grown by the Czochralski technique have been examined using the method of fast withdrawal from the melt. Initially, the interface shape is convex, then transforms gradually into a sigmoidal shape, becomes nearly planar at about one third of the final crystal length, and finally assumes a concave profile with progressively increasing curvature. The nearly planar interface has a double-facet structure, with an annular facet at the edge of the crystal in addition to the central (111) facet. Formation of the annular facet is accompanied by a giant oscillation of the pull rate when the maximum average pull rate is exceeded. Such oscillation is detrimental to crystal quality, since it introduces a region of high dislocation density. An average pull rate maximum of 2 cm/h has been found to allow for a smooth growth of 200 mm diameter crystals. The origin of the pull rate perturbation is discussed in terms of an instantaneous change in the equilibrium shape of the meniscus.
Document ID
19910037021
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Roth, M.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Azoulay, M.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Gafni, G.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Mizrachi, M.
(Israel Atomic Energy Commission, Soreq Nuclear Research Centre Yavne, United States)
Date Acquired
August 15, 2013
Publication Date
January 1, 1990
Publication Information
Publication: Journal of Crystal Growth
Volume: 99
Issue: 1-4,
ISSN: 0022-0248
Subject Category
Solid-State Physics
Accession Number
91A21644
Distribution Limits
Public
Copyright
Other

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