Recent Developments in the Fabrication and Operation of Germanium Detectors

Vetter, K.

doi:10.1146/annurev.nucl.56.080805.140525

Cited by 62 publications

(53 citation statements)

References 114 publications

(90 reference statements)

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“…The substitutional sites are highlighted in black and dark red for Ga and Te, respectively. The Ga sites indicated by 1 and 3 are qualitatively different by involving either in-plane Ga-Ga bonds (1) or perpendicular Ga-Ga bonds (3). We refer to the in-plane GaGa bonds are "horizontal" and perpendicular Ga-Ga bonds as "vertical" in the remainder of this text.…”

Section: Structure and Electronic Charactermentioning

confidence: 99%

“…The requirement for cryogenic cooling limits large scale applications and increases the cost of Ge-based devices. 3 The other prevalent material is Cd x Zn 1−x Te (CZT), which has a band gap large enough for low-noise operation at room-temperature. However, the addition of ( 10 at%) Zn to CdTe to form the CZT alloy introduces significant internal strains to the lattice, making the growth of large defect-free single crystals of CZT difficult.…”

Section: Introductionmentioning

confidence: 99%

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Ab initioguided optimization of GaTe for radiation detection applications

Leão

Lordi

2011

Phys. Rev. B

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The development of semiconductor-based radiation detectors that display high energy resolution while operating at room temperature is a pressing need for both scientific applications as well as homeland security. Practice has proven that the real performance of materials in such applications is often hindered by intrinsic defects and accidental impurities. Experimental efforts to improve the properties of such materials are both time consuming and costly, since they rely largely on trial and error. In this paper, the properties of gallium telluride (GaTe)-a high Z, moderate band gap semiconductor-are investigated for room-temperature radiation detection applications. Systematic theoretical modeling based on density functional theory calculations is used to suggest experimental processes to grow this semiconductor with optimal properties, by judiciously identifying the most detrimental native defects and devising ways to minimize their occurrence as well as compensating their electronic impact on the crystal. The analysis suggests that material grown Ga-rich would have significantly higher resistivity, carrier mobilities, and carrier lifetimes compared to Te-rich material. In addition, Ge doping and In doping can be effective for carrier compensation of the material. Doping with Ge can be especially effective, if the ambipolar nature of substitutional incorporation on both Ga and Te sites is exploited.

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Section: Structure and Electronic Charactermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ab initioguided optimization of GaTe for radiation detection applications

Leão

Lordi

2011

Phys. Rev. B

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“…In semiconductor detectors, a small band gap of few eV only allows very sensitive high-resolution detectors. Germanium detectors have been established as standard in terrestrial nuclear-physics experiments, and also space borne cosmic gamma-ray experiments; Ge detectors have been reviewed recently [134]. In recent years, CdZnTl detectors have become popular, because they can be operated at room temperature, rather than the cryogenic temperatures required for Ge detectors, at nearly similar performance.…”

Section: Gamma-ray Spectrometrymentioning

confidence: 99%

Cosmic Gamma-Ray Spectroscopy

Diehl¹

2013

Astronomical Review

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Penetrating gamma-rays require complex instrumentation for astronomical spectroscopy measurements of gamma-rays from cosmic sources. Multiple-interaction detectors in space combined with sophisticated postprocessing of detector events on ground have lead to a spectroscopy performance which is now capable to provide new astrophysical insights. Spectral signatures in the MeV regime originate from transitions in the nuclei of atoms (rather than in their electron shell). Nuclear transitions are stimulated by either radioactive decays or high-energy nuclear collisions such as with cosmic rays. Gamma-ray lines have been detected from radioactive isotopes produced in nuclear burning inside stars and supernovae, and from energetic-particle interactions in solar flares. Radioactive-decay gamma-rays from 56 Ni directly reflect the source of supernova light. 44 Ti is produced in core-collapse supernova interiors, and the paucity of corresponding 44 Ti gamma-ray line sources reflects the variety of dynamical conditions herein.26 Al and 60 Fe are dispersed in interstellar space from massive-star nucleosynthesis over millions of years. Gamma-rays from their decay are measured in detail by gamma-ray telescopes, astrophysical interpretations reach from massive-star interiors to dynamical processes in the interstellar medium. Nuclear de-excitation gamma-ray lines have been found in solar-flare events, and convey information about energetic-particle production in these events, and their interaction in the solar atmosphere. The annihilation of positrons leads to another type of cosmic gamma-ray source. The characteristic annihilation gamma-rays at 511 keV have been measured long ago in solar flares, and now throughout the interstellar medium of our Milky Way galaxy. But now a puzzle has appeared, as a surprising predominance of the central bulge region was determined. This requires either new positron sources or transport processes not yet known to us. In this paper we discuss instrumentation and data processing for cosmic gamma-ray spectroscopy, and the astrophysical issues and insights from these measurements.

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“…Despite the inconvenience and cost of permanent 1 9 8 2 1 9 8 3 1 9 8 4 1 9 8 5 1 9 8 6 1 9 8 7 1 9 8 8 1 9 8 9 1 9 9 0 1 9 9 1 1 9 9 2 1 9 9 3 1 9 9 4 1 9 9 5 1 9 9 6 1 9 9 7 1 9 9 8 1 9 9 9 2 0 0 0 liquid nitrogen cooling, Ge(Li) crystals could never be allowed to warm up, as the Lithium would drift out of the crystal, destroying thereby the detector. HPGe detectors can be allowed to warm up to room temperature when not in use (Vetter 2007).…”

Section: Ge Crystals For X-ray Detectorsmentioning

confidence: 99%

Germanium: environmental occurrence, importance and speciation

Rosenberg

2008

Rev Environ Sci Biotechnol

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This review discusses the various aspects of the bio-geochemistry of germanium, and of its technological, economical and environmental importance. Despite the relatively low annual production and consumption of this semi-metal (ca. 80 metric tons/a) there are important technological applications of this element in the semiconductor, infrared optics and fibre optics/telecommunication industries. A small, but not insignificant fraction of this element is used for the production of pharmaceuticals and nutritional supplements, although its actual merits have not been fully demonstrated yet, while they are opposed to chronic toxicity of the element when being administrated at relatively high doses for an extended period of time. Neither the exact mechanism of action in the case of cancer treatment or the treatment of infectious diseases is known, nor the reason for the toxicity of inorganic species of this element. In plants, Ge can partially substitute for B in the case of boron deficiency, although deficiency symptoms are still seen with a lag period of ca. one to three weeks. In biogeochemical respect, germanium and silicon react very similar, as if Ge were a very heavy isotope of Si. Their molar ratio is typically in the order of 0.6 9 10 -6 , with significant deviations only where germanium is complexed and transported, e.g., by humic-rich waters. Germanium is a very conservative element in biogeochemical terms: It hardly shows involvement in any biogeochemical reaction cycles and is mainly present in the form of complexes or hydroxo-compounds of the tetravalent germanium. The only naturally occurring organogermanium compounds are mono-and dimethylgermanium which are believed to be formed by microbiological activity in continental zones containing Ge-rich minerals, and then are leached into rivers, and finally into the open sea. It becomes evident that, although very sophisticated technological uses of germanium exist, a better understanding of its biogeochemical importance, cycling and reactivity must still be developed.

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Recent Developments in the Fabrication and Operation of Germanium Detectors

Cited by 62 publications

References 114 publications

Ab initioguided optimization of GaTe for radiation detection applications

Ab initioguided optimization of GaTe for radiation detection applications

Cosmic Gamma-Ray Spectroscopy

Germanium: environmental occurrence, importance and speciation

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