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  • Other Sources  (10)
  • 1
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    Pyroelectric detector development for the Radiation Measurement system (1993)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: A new class of high detectivity pyroelectric detectors developed for optimization of the radiation measurement system within the framework of the Atmospheric Radiation Measurement program is described. These devices are intended to provide detectivities of up to about 10 exp 11 cm Hz exp 0.5/W with cooling to about 100 K required for the detector focal plane.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: ; : Analysis of optica
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  • 2
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    Ge:Be far infrared photoconductors (1983)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: Some conclusions reached are as follow. Ge:Be detectors provide lower Noise Equivalent Power (NEP) and higher responsivities than state of the art Ge:Ga detectors at 42 microns. Reliable Be doping was achieved with Czochralski growth from a carbon susceptor under vacuum. The photoconductive behavior of Ge:Be detectors is strongly influenced by the concentration of residual shallow impurities. Optimization of Ge:Be detectors requires both a low concentration and precise compensation of shallow acceptors.
    Keywords: OPTICS
    Type: NASA. Ames Research Center, Infrared Detector Technology Workshop; 10 p
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  • 3
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    Germanium Blocked Impurity Band (BIB) detectors (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Information is given in viewgraph form. The advantages of the Si blocked impurity band (BIB) detector invented by M. D. Petroff and M. G. Stabelbroek are noted: smaller detection volume leading to a reduction of cosmic ray interference, extended wavelength response because of dopant wavefunction overlap, and photoconductive gain of unity. It is argued that the stated advantages of Si BIB detectors should be realizable for Ge BIB detectors. Information is given on detector development, subtrate choice and preparation, wafer polising, epitaxy, characterization of epi layers, and preliminary Ge BIB detector test results.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Ames Research Center, Proceedings of the Third Infrared Detector Technology Workshop; p 85-115
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  • 4
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    Stressed Ge:Ga photoconductors for space-based astronomy. (Is there life beyond 120 micron) (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Information is given in viewgraph form. Information is given on the characteristics of stressed Ge:Ga, a spring type stress cavity, mounting hardware, materials parameters affecting dark current, and the behavior of low dark current stressed Ge:Ga. It is concluded that detectors exist today for background-limited detection at 200 microns, that researchers are narrowing in on the significant parameters that effect dark current in stressed photoconductors, that these findings may be applied to other photoconductor materials, and that some creative problem solving for an ionizing effect reset mechanism is needed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Ames Research Center, Proceedings of the Third Infrared Detector Technology Workshop; p 5-2
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  • 5
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    Far-infrared observations of shocked CO in Orion (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The J = 27-26 and J = 30-29 transitions of CO have been detected in the Orion molecular cloud. These detections, together with an improved measurement of the J = 21-20 transition, allow estimation of the temperature and density of the shocked material and the fractional abundance of CO. By solving the equations of detailed balance for J less than or equal to 50 and fitting the data to a two-component model consistent with earlier 2-micron and 12-micron H2 observations, it is shown that the hot (2000 K) component has a density of approximately 1.0 x 10 to the 6th/cu cm, while the cooler component lies in the range of 400-1000 K and is 2-5 times more dense. Approximately 25% of the carbon is in the form of CO. The spatial extent of the hot CO has also been examined by observing the J = 21-20 transition at a number of positions, and it is found to be distributed similarly to the H2 lines. In addition, a search for J = 21-20 and J = 22-21 CO emission from six other sources has resulted in 3-standard-deviation upper limits of a factor of 10 below the intensity of the Orion lines.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 247
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  • 6
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    Detection of CO J = 21-20 /124.2 microns/ and J = 22-21 /118.6 microns/ emission from the Orion nebula (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The first observation of far-infrared molecular line emission from the interstellar medium is reported. Strong emission from the J = 21-20 and J = 22-21 rotational transitions of carbon monoxide was detected in the Kleinmann-Low/shocked H2 region of the Orion Molecular Cloud. The results imply that the region is optically thin in these lines and that much of the carbon is in the form of CO. This work also represents the first use of an antimony-doped germanium photoconductor in an astronomical application.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
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  • 7
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    Three holes bound to a double acceptor - Be(+) in germanium (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A double acceptor binding three holes has been observed for the first time with photoconductive far-infrared spectroscopy in beryllium-doped germanium single crystals. This new center, Be(+), has a hole binding energy of about 5 meV and is only present when free holes are generated by ionization of either neutral shallow acceptors or neutral Be double acceptors. The Be(+) center thermally ionizes above 4 K. It disappears at a uniaxial stress higher than about a billion dyn/sq cm parallel to (111) as a result of the lifting of the valence-band degeneracy.
    Keywords: SOLID-STATE PHYSICS
    Type: Physical Review Letters (ISSN 0031-9007); 51; Sept. 19
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  • 8
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    High purity isotopically enriched Ge-70 and Ge-74 single crystals - Isotope separation, growth, and properties (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-08-27
    Description: Ge-70 and Ge-74 isotopes were successfully separated from natural Ge, and were zone purified. Several highly enriched, high purity Ge-70 and Ge-74 single crystals were grown by the vertical Bridgman method. The growth system was designed for reliable growth of low dislocation density, high purity Ge single crystals of about 4 g weight. A Ge-70 and a Ge-74 crystal were selected for complete characterization. In spite of the large surface-to-volume ratio of these ingots, both Ge-70 and Ge-74 crystals contain low electrically active chemical net-impurity concentrations of about 2 x 10 exp 12/cu cm, which is 2 orders of magnitude better than that of Ge-74 crystals previously grown by two different groups. Isotopic enrichment of the Ge-70 and the Ge-74 crystals is 96.3 percent and 96.8 percent, respectively. The residual donors and acceptors present in both crystals were identified as phosphorus and copper, respectively. In addition, less than 10 exp 11/cu cm Ga, Al, and In were found in the Ge-70 crystal.
    Keywords: SOLID-STATE PHYSICS
    Type: Journal of Materials Research (ISSN 0884-2914); 8; 6; p. 1341-1347.
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  • 9
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    Ion-implanted extrinsic Ge photodetectors with extended cutoff wavelength (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Far-IR Ge detectors fabricated using boron ion implantation are shown to exhibit operating characteristics compatible with requirements for low background applications. Device parameters such as low dark currents, reasonably good sensitivity, and extended wavelength threshold demonstrate that ion-implanted Ge far-IR detectors offer promise for use in astrophysics instrumentation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Physics Letters (ISSN 0003-6951); 58; 1431-143
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  • 10
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    Extrinsic germanium photoconductors for far-IR astronomy: Research results and works in progress (1996)
    In:  CASI
    Details
    Publication Date: 2019-08-15
    Description: Some Ge:Ga and Ge:Sb photoconductor materials and detectors that are currently under development are reported. The best Ge:Ga devices exhibit dark currents of lower than 200 electrons/s, with a concurrent responsivity of 2 A/W and a detective quantum efficiency (DQE) of 5 percent. For higher backgrounds, an operating temperature of 3 K can be used. This increases the DQE to 7 percent and the responsivity to 4.5 A/W. Investigations were initiated into n-type Ge:Sb as an alternative photoconductive material. Two crystals of Ge:Sb were grown and a number of test detectors were fabricated and evaluated. At 2 K, the best device produced dark currents of less than 100 electrons/s with concurrent responsivity of 1 A/W and DQE of 4 percent, and at 3 K, produced currents of 10(exp 5) electrons/s with a DQE of 7 percent and a responsivity of 4 A/W. Using p-type Ge:Ga crystals, two dimensional monolithic photoconductor arrays are being constructed. Future work will focus on measuring pixel-to-pixel homogeneity, cross talk issues, overall sensitivity and suitability for photometric instruments.
    Keywords: Spacecraft Instrumentation
    Type: The 30th ESLAB Symposium on Submillimetre and Far-Infrared Space Instrumentation; 21-24; ESA-SP-388
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