Abstract Submitted
for the DNP16 Meeting of
The American Physical Society
Purification of Germanium Crystals by Zone Refining1 KYLER
KOOI, GANG YANG, DONGMING MEI, Department of Physics, University of
South Dakota — Germanium zone refining is one of the most important techniques
used to produce high purity germanium (HPGe) single crystals for the fabrication
of nuclear radiation detectors. During zone refining the impurities are isolated to
different parts of the ingot. In practice, the effective isolation of an impurity is
dependent on many parameters, including molten zone travel speed, the ratio of
ingot length to molten zone width, and number of passes. By studying the theory
of these influential factors, perfecting our cleaning and preparation procedures, and
analyzing the origin and distribution of our impurities (aluminum, boron, gallium,
and phosphorous) identified using photothermal ionization spectroscopy (PTIS), we
have optimized these parameters to produce HPGe. We have achieved a net impurity level of ∼ 1010 /cm3 for our zone-refined ingots, measured with van der Pauw
and Hall-effect methods. Zone-refined ingots of this purity can be processed into
a detector grade HPGe single crystal, which can be used to fabricate detectors for
dark matter and neutrinoless double beta decay detection.
1 This
project was financially supported by DOE Grant (DE-FG02-10ER46709)and
the State Governor’s Research Center.
Kyler Kooi
Department of Physics, University of South Dakota
Date submitted: 11 Jul 2016
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