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  • 1
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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
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Parametric amplification and oscillation at 36 GHz using a point-contact Josephson junction (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The paper reports observation of doubly degenerate parametric amplification and oscillation at 36 GHz from a single point-contact Josephson junction. The experimental results agree qualitatively with theoretical calculations based on the resistively shunted junction model. The estimated noise temperature of an amplifier with 11 dB net gain is consistent with zero, but has an upper limit of 50 K. Attempts to observe parametric amplification in the singly degenerate mode with a pump frequency of 72 GHz were not successful.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Journal of Applied Physics; 48; Mar. 197
    Format: text
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  • 3
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    Near millimeter wave bandpass filters (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The properties of bandpass filters for broadband photometry are reported in the 3-12/cm frequency range. The filters are based on a combination of capacitive grids deposited on thick Mylar substrates and are designed to have very high out-of-band rejection. Low frequencies are blocked by a thick grill that consists of a hexagonal grid of circular holes in a thick metal plate.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Applied Optics; 20; Apr. 15
    Format: text
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  • 4
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    Performance of Ge:Ga far infrared detectors (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A systematic study was carried out of the properties of Ge:Ga photoconductive infrared detectors for wavelengths approx. 100 micron. The detectors studied were made from Ge:Ga with acceptor concentration N sub A approx. 2 x 10 exp 14/cu cm with both low compensation (10 exp -2) and ultralow compensation (10 exp -4). Noise measurements have been made as a function of background photon rate, bias voltage, and chopping frequency. Detective quantum efficiencies approaching unity have been observed over a side range of experimental parameters. Photocurrent has been measured as a function of voltage and temperature. Hall mobility and lifetime have been measured to determine their effect on detector properties. A small potential drop has been observed in nominally ohmic contacts produced by implantation of B ions.
    Keywords: OPTICS
    Type: NASA. Ames Research Center, Infrared Detector Technology Workshop; 16 p
    Format: text
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  • 5
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    Improved fabrication techniques for infrared bolometers (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Techniques are described for producing improved infrared bolometers from doped germanium. Ion implantation and sputter metalization have been used to make ohmic electrical contacts to Ge:Ga chips. This method results in a high yield of small monolithic bolometers with very little low-frequency noise. When one of these chips is used as the thermometric element of a composite bolometer, it must be bonded to a dielectric substrate. The thermal resistance of the conventional epoxy bond has been measured and found to be undesirably large. A procedure for soldering the chip to a metalized portion of the substrate is described which reduced this resistance. The contribution of the metal film absorber to the heat capacity of a composite bolometer has been measured. The heat capacity of a NiCr absorber at 1.3 K can dominate the bolometer performance. A Bi absorber has significantly lower heat capacity. A low temperature blackbody calibrator has been built to measure the optical responsivity of bolometers. A composite bolometer system with a throughput of approx. 0.1 sr sq cm was constructed using the new techniques. In negligible background it has an optical NEP of 3.6 10((exp -15) W/sq root of Hz at 1.0 K with a time constant of 20 ms. The noise in this bolometer is white above 2.5 Hz and is somewhat below the value predicted by thermodynamic equilibrium theory. It is in agreement with calculations based on a recent nonequilibrium theory.
    Keywords: OPTICS
    Type: NASA. Ames Research Center, Infrared Detector Technology Workshop; 24 p
    Format: text
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  • 6
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    Accurate experimental and theoretical comparisons between superconductor-insulator-superconductor mixers showing weak and strong quantum effects (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: A systematic study of the gain and noise in superconductor-insulator-superconductor mixers employing Ta based, Nb based, and Pb-alloy based tunnel junctions was made. These junctions displayed both weak and strong quantum effects at a signal frequency of 33 GHz. The effects of energy gap sharpness and subgap current were investigated and are quantitatively related to mixer performance. Detailed comparisons are made of the mixing results with the predictions of a three-port model approximation to the Tucker theory. Mixer performance was measured with a novel test apparatus which is accurate enough to allow for the first quantitative tests of theoretical noise predictions. It is found that the three-port model of the Tucker theory underestimates the mixer noise temperature by a factor of about 2 for all of the mixers. In addition, predicted values of available mixer gain are in reasonable agreement with experiment when quantum effects are weak. However, as quantum effects become strong, the predicted available gain diverges to infinity, which is in sharp contrast to the experimental results. Predictions of coupled gain do not always show such divergences.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Journal of Applied Physics (ISSN 0021-8979); 63; 2479-249
    Format: text
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