Effect of annealing on contact performance and electrical properties of p-type high purity germanium single crystal

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

doi:10.1007/s00339-012-7518-x

Cited by 14 publications

(9 citation statements)

References 13 publications

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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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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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“…Zone refining of commercially available Ge ingots is a prerequisite for growing detector-grade single crystals. We have developed zone-refining methods [54][55][56] that advance approaches to reducing impurity level from a commercially-achievable level of ∼(1-3)×10 14 /cm 3 to a level of ∼10 10 /cm 3 , which is needed to grow crystals without doping for novel detectors. The dominant impurities in Ge ingots are B, Al, Ga, P, and Al monoxide (AlO).…”

Section: Development Of a Detector With Internal Amplification Of Cha...mentioning

confidence: 99%

Direct detection of MeV-scale dark matter utilizing germanium internal amplification for the charge created by the ionization of impurities

et al. 2018

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Light, MeV-scale dark matter (DM) is an exciting DM candidate that is undetectable by current experiments. A germanium (Ge) detector utilizing internal charge amplification for the charge carriers created by the ionization of impurities is a promising new technology with experimental sensitivity for detecting MeV-scale DM. We analyze the physics mechanisms of the signal formation, charge creation, charge internal amplification, and the projected sensitivity for directly detecting MeV-scale DM particles. We present a design for a novel Ge detector at helium temperature (∼ 4 K) enabling ionization of impurities from DM impacts. With large localized E-fields, the ionized excitations can be accelerated to kinetic energies larger than the Ge bandgap at which point they can create additional electron-hole pairs, producing intrinsic amplification to achieve an ultra-low energy threshold of ∼ 0.1 eV for detecting low-mass DM particles in the MeV scale. Correspondingly, such a Ge detector with 1 kg-year exposure will have high sensitivity to a DM-nucleon cross section of ∼ 5 × 10 −45 cm 2 at a DM mass of ∼ 10 MeV/c 2 and a DM-electron cross section of ∼ 5 × 10 −46 cm 2 at a DM mass of ∼ 1 MeV/c 2 .

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“…In our group, the HPGe crystals were grown through the Czochralski method using the zone-refined ingots produced at USD from commercial raw materials [64][65][66][67]. The growth process and the characterization method were described in several papers from our group [45,[68][69][70]. In this paper, we will focus on the fabrication of the detectors.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and characterization of high-purity germanium detectors with amorphous germanium contacts

et al. 2019

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Large, high-purity, germanium (HPGe) detectors are needed for neutrinoless doublebeta decay and dark matter experiments. Currently, large (> 4 inches in diameter) HPGe crystals can be grown at the University of South Dakota (USD). We verify that the quality of the grown crystals is sufficient for use in large detectors by fabricating and characterizing smaller HPGe detectors made from those crystals. We report the results from eight detectors fabricated over six months using crystals grown at USD. Amorphous germanium (a-Ge) contacts are used for blocking both electrons and holes. Two types of geometry were used to fabricate HPGe detectors. As a result, the fabrication process of small planar detectors at USD is discussed in great detail. The impact of the procedure and geometry on the detector performance was analyzed for eight detectors. We characterized the detectors by measuring the leakage current, capacitance, and energy resolution at 662 keV with a Cs-137 source. Four detectors show good performance, which indicates that crystals grown at USD are suitable for making HPGe detectors.

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Effect of annealing on contact performance and electrical properties of p-type high purity germanium single crystal

Cited by 14 publications

References 13 publications

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

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

Direct detection of MeV-scale dark matter utilizing germanium internal amplification for the charge created by the ionization of impurities

Fabrication and characterization of high-purity germanium detectors with amorphous germanium contacts

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