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  • Infrared Astronomy  (2)
  • 71.55.Eq  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Si DX centers in GaAs at large hydrostatic pressures (1991)
    Springer
    Applied physics 53 (1991), S. 26-31 
    Details
    ISSN: 1432-0630
    Keywords: 71.55.Eq ; 78.30.Fs ; 63.20.Pw ; 61.70.Tm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A number of experimental and theoretical studies indicate that DX centers in GaAs, its alloys and other III–V semiconductors have negative U properties. Using far infrared localized vibrational mode (LVM) spectroscopy of Si donors in GaAs under large hydrostatic pressure in a diamond anvil cell we have discovered an LVM of the Si DX center. From the ratio of the LVM absorption lines of SiGa and SiDX and the compensation in our GaAs samples, we show unambiguously that two electrons are trapped when the ionized shallow Si donors transform into negatively charged DX centers, in full agreement with the negative U model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00323430
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The MPE/UCB far-infrared imaging Fabry-Perot interferometer (FIFI) (1991)
    Springer
    International journal of infrared and millimeter waves 12 (1991), S. 859-884 
    Details
    ISSN: 1572-9559
    Keywords: Spectrometer ; Infrared Astronomy ; Infrared Techniques ; Detector Array ; Cryogenic Electronics ; Fabry-Perot ; Cryogenic ; Imaging ; Instrument Function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract FIFI is an imaging spectrometer with two or three Fabry-Perot interferometers (FPI) in series for airborne astronomical observations in the far-infrared range (λ=40...200μm). It employs 5×5 arrays of photoconducting detectors and offers spectral resolutions as small as 2km/s. Resolution and bandwidth can be set over a wide range to match a variety of astronomical sources. Cryogenic optics minimizes thermal background radiation and provides for in-flight step tunable spatial resolution. At 158 μm wavelength the background-limited NEP is 3 × 10-15W/ℚHz at 40 km/s resolution and with two FPI's; with three FPI's the expected NEP is ≤10-15W√Hz at 5 km/s resolution. The frequency-chopping mode of the high-resolution Fabry-Perot allows for line detection in extended objects. Absolute internal flux calibration ensures adequate “flat fielding” of the array elements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01009647
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  • 3
    Electronic Resource
    Electronic Resource
    Stressed and unstressed Ge:Ga detector arrays for airborne astronomy (1992)
    Springer
    International journal of infrared and millimeter waves 13 (1992), S. 1689-1707 
    Details
    ISSN: 1572-9559
    Keywords: Infrared Astronomy ; Infrared Techniques ; Photoconductive Detector Array ; Cryogenic Electronics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have constructed and used two dimensional arrays of both unstressed and stressed Ge:Ga photoconductive detectors for far-infrared astronomy from the Kuiper Airborne Observatory (KAO). The 25 element (5×5) arrays are designed for a new cryogenically cooled spectrometer, the MPE/UCB Far-Infrared Imaging Fabry-Perot Interferometer (FIFI). All of the pixels for the stressed array performed well on the first flights with FIFI; 25% of the detectors in the array are more sensitive than our best single element detector, with background limited noise equivalent powers (NEPs)≲3.0×10−15 W Hz−1/2 at 158 μm and 40 km s−1 spectral resolution. The average array element performs within±15% of this value. With a bias field of 0.1 V/cm, the average detector response is 20±6 Amp/Watt at 158 μm. The cutoff wavelength and response also compare well with our single element detectors. The unstressed array delivers significantly better performance than our single element detector due to the lower thermal background in the new spectrometer. The average background limited NEp at 88 μm and 35 km s−1 spectral resolution is ∼7×10−15 W Hz−1/2. The least sensitive pixel is only 40% less sensitive. The unstressed array response at 88 μm with a bias field of 1 V/cm is 5±1 Amp/Watt. Twenty four of the 25 elements worked on the first flights-on subsequent flights all channels have worked. Some of the exciting new science possible with far-infrared detector arrays is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01010739
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    Paper (German National Licenses)
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