Dislocation density control in high-purity germanium crystal growth

Wang, Guojian; Guan, Yutong; Mei, Hao; Mei, Dongming; Yang, Gang; Govani, Jayesh; Khizar, M.

doi:10.1016/j.jcrysgro.2013.11.075

Cited by 24 publications

(20 citation statements)

References 21 publications

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“…Driven primarily by the need of Ge detectors with extremely low cosmogenic activation of Ge isotopes for ton-scale dark matter and neutrinoless double-beta decay experiments, USD has built the capacity in zone refining [44][45][46], crystal growth [2][3][4][5][6] and detector development to make Ge detector development in an underground laboratory possible. Using the USD-grown crystals, we have investigated the performance of the planar detectors fabricated with a-Ge contacts.…”

Section: Resultsmentioning

confidence: 99%

“…Growing Ge crystals and fabricating detectors underground where the experiment will be built is the best option to reduce the background events from cosmogenic activation processes. High-purity Ge (HPGe) crystals have been grown at the University of South Dakota (USD) to pave the way for fabricating Ge crystals and detectors underground [2][3][4][5][6]. Low background Ge detectors are a well-accepted methodology in the search for dark matter [7][8][9] and neutrinoless double-beta decay [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

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Investigation of amorphous germanium contact properties with planar detectors made from USD-grown germanium crystals

Wei

Meng

et al. 2018

J. Inst.

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A: The characterization of detectors fabricated from home-grown crystals is the most direct way to study crystal properties. We fabricated planar detectors from high-purity germanium (HPGe) crystals grown at the University of South Dakota (USD). In the fabrication process, a HPGe crystal slice cut from a USD-grown crystal was coated with a high resistivity thin film of amorphous Ge (a-Ge) followed by depositing a thin layer of aluminum on top of the a-Ge film to define the physical area of the contacts. We investigated the detector performance including the I-V characteristics, C-V characteristics and spectroscopy measurements for a few detectors. The results document the good quality of the USD-grown crystals and electrical contacts. K: amorphorous germanium contacts, planar germanium detectors, leakage current, gamma ray spectroscopy 1Corresponding author.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation of amorphous germanium contact properties with planar detectors made from USD-grown germanium crystals

Wei

Meng

et al. 2018

J. Inst.

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“…High-purity germanium crystals have been grown on a weekly basis in our labs at the University of South Dakota [34][35][36][37][38][39][40][41]. Several germanium samples obtained from a detector-grade crystal (NO.20 [42]) grown in our lab with measured Hall mobility µ H larger than 36000 cm 2 /(V·s) were used for our investigation in this work.…”

Section: Resultsmentioning

confidence: 99%

The impact of neutral impurity concentration on charge drift mobility in p-type germanium

Mei¹,

Mei²,

Wang³

et al. 2016

J. Inst.

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We reported a new result of the neutral impurity scattering of holes that has impact on the charge drift mobility in high purity p-type germanium crystals at 77 Kelvin. The charge carrier concentration, mobility and resistivity are measured by Hall Effect system at 77 Kelvin. We investigated the contribution to the total charge drift mobility from ionized impurity scattering, lattice scattering, and neutral impurity scattering with the best theoretical models and experimental data. Several samples with measured Hall mobility from the grown crystals are used for this investigation. With the measured Hall mobility and ionized impurity concentration as well as the theoretical models, we calculated the neutral impurity concentration by the Matthiessen's rule. As a result, the distributions of the neutral impurity concentrations with respect to the radius of the crystals are obtained. Consequently, we demonstrated that neutral impurity scattering is a significant contribution to the charge drift mobility, which has dependence on the concentration of neutral impurities in a given germanium crystal.

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“…One crystal was grown under constant Ar flow, while the other was grown under a constant flow of ultra-pure H 2 purified in a Pd cell. For radiation-detector applications, a low and homogeneous dislocation density between 10 2 and 10 4 cm À2 is required (Wang et al, 2014). Therefore, a Dash neck procedure was used to get rid of the initial dislocations.…”

Section: Methodsmentioning

confidence: 99%

Dynamical X-ray diffraction imaging of voids in dislocation-free high-purity germanium single crystals

et al. 2020

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White-beam X-ray topography has been performed to provide direct evidence of micro-voids in dislocation-free high-purity germanium single crystals. The voids are visible because of a dynamical diffraction contrast. It is shown that voids occur only in dislocation-free parts of the crystal and do not show up in regions with homogeneous and moderate dislocation density. It is further suggested that the voids originate from clustering of vacancies during the growth process. A general method is proposed to verify the presence of voids for any crystalline material of high structural perfection.

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Dislocation density control in high-purity germanium crystal growth

Cited by 24 publications

References 21 publications

Investigation of amorphous germanium contact properties with planar detectors made from USD-grown germanium crystals

Investigation of amorphous germanium contact properties with planar detectors made from USD-grown germanium crystals

The impact of neutral impurity concentration on charge drift mobility in p-type germanium

Dynamical X-ray diffraction imaging of voids in dislocation-free high-purity germanium single crystals

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