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Defect Density Comparison of Detached versus Attached Bridgman Grown Germanium CrystalsSemiconductor Bridgman growth without contact between the growing crystal and the growth ampoule has been observed on Earth in the last few years during several experiments. Previously, this so-called detached or dewetted growth phenomenon occurred preferentially under microgravity conditions due to the absence of the hydrostatic pressure. Many theoretical as well as experimental investigations helped to provide a better understanding of the mechanism and to identify the parameters leading to the detachment. Thus, recent attempts to get stable detached growth under terrestrial conditions by Duffar et al. growing III-V compounds and our own group with germanium and germanium-silicon alloys were frequently successful. At this conference we present the results of several germanium growth experiments performed in pyrolytic boron nitride containers. To exert an influence on the pressure ratio above and below the melt we used closed-bottom and open-bottom containers. This resulted in mainly detached-grown single crystals with the closed-bottom crucibles and attached single crystals with the open-bottom tubes. Evidence of detached growth is obtained from the crystal surface with a combination of axial profilometer scans and optical and electron microscopy. Detailed investigations of the defect structure, which is the main focus of this presentation, have shown an improvement of the crystal quality in the detached-grown samples, with a strong reduction of the etch pit density by about two orders of magnitude.
Document ID
20020022685
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Schweizer, M.
(Universities Space Research Association Huntsville, AL United States)
Cobb, S. D.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Volz, M. P.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Szofran, F. R.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Whitaker, Ann F.
Date Acquired
August 20, 2013
Publication Date
January 1, 2001
Subject Category
Solid-State Physics
Meeting Information
Meeting: American Crystal Growth Conference
Location: Burlington, VT
Country: United States
Start Date: August 13, 2001
Funding Number(s)
CONTRACT_GRANT: NCC8-66
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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