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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 3194-3197 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: At room temperature different GaAs Schottky barrier diodes with submicrometer structure and ∼fF capacitance C have been investigated in a heterodyne receiver. Using microwave sources and submillimeter lasers as the local oscillator (LO) they show that the number of electrons Ne passing through the Schottky contact each LO cycle is constant and is a characteristic value for each diode type. This is expressed by the experimentally derived equation for the optimum current I=Ne eν (e is the electronic charge and ν the frequency of the radiation). The required optimum LO voltage amplitude VLO is independent of operating frequency and fulfills the equation VLO=(Ne e)/2C.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 4243-4248 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Video detection experiments from 0.7 to 30 THz and mixing experiments at 30 THz have been performed with GaAs Schottky-barrier diodes and W-Ni metal-insulator-metal (MIM) diodes. Above approximately 12 THz the MIM diode is the more sensitive video detector (a factor of 5–10 at 30 THz). Difference frequencies up to 34 GHz were generated by mixing the radiation of two adjacent CO2 laser lines and a microwave source in a Schottky-barrier diode. The dependence of the mixing signal on different diode parameters (doping density, plasma frequency, cutoff frequency) and on bias current was measured. Compared with MIM diodes at 30 THz the Schottky-barrier diodes are less efficient for mixing (a factor of 104). The results suggest that thermionic emission is the dominant physical mechanism responsible for video detection and mixing at 30 THz.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 1359-1361 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have observed intervalence band laser action in Al-doped germanium crystals with volumes as small as 0.03 cm3, one order of magnitude smaller than previously studied p-Ge laser crystals. A duty cycle of 1.5×10−4 was achieved. We show evidence that crystal heating plays a key role in the duration of the emission pulse and have measured a maximum pulse length of 11 μs for a 0.43 cm3, Ga-doped germanium crystal. Such progress in the understanding and performance of p-Ge hot hole lasers marks a significant step toward continuous wave operation.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 290-293 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A laser magnetic resonance spectrometer for the far-infrared region is described. It is based on an optically pumped far-infrared laser. Zeeman tuning of the energy levels of the investigated molecule is achieved by using permanent magnets. With this setup it is possible to reach a magnetic flux density as high as 0.5 T. The design of the spectrometer is very compact compared to conventional laser magnetic resonance spectrometers based on superconducting or watercooled electromagnets. This makes it a promising tool for analytic purposes either in the laboratory or for field studies. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 3543-3545 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the influence of high repetition rates, up to 300 Hz, on four pulsed p-type germanium lasers. The maximum electric input power which terminates laser action via heating is a characteristic value for each crystal. We show magnetic field sweeps and introduce a diagram which connects the dynamical behavior of light and heavy holes to optical phonons and impurity states. We find that temperature is an essential key for the understanding of the laser action. High repetition rates or continuous wave operation may be achieved with proper design of the crystal and its cooling environment. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 3075-3077 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on intervalence-band laser emission from Be- and Zn-doped germanium crystals. The duty cycle of 10−3 at a repetition rate of 1 kHz is one order of magnitude larger than the highest duty cycle reported for p-Ge lasers doped by group II acceptors. This improvement is due to the much larger hole binding energy of double acceptors Be and Zn which results in a strong reduction of the internal absorption of the generated far-infrared radiation. Laser action has been achieved with crystal volumes as small as 0.04 cm−3, and a laser pulse length of 25 μs has been reached. Germanium crystals doped with these acceptors may offer an opportunity for achieving the ultimate goal of continuous wave operation. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 5326-5330 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dependence on temperature of the Schottky barrier height of Pt on n-GaAs is reported. Two different behaviors are observed. The Schottky contacts of one group have a mean barrier height of 1.018 eV and a temperature coefficient of −0.23 meV/K while the contacts of the other group have a significantly lower barrier height of 0.922 eV which is almost independent of the temperature. These results are interpreted on the basis of recent models of Fermi level pinning. While the Fermi level in the diodes of the first group is pinned to a charge neutrality level, it is pinned by defects in the diodes of the second group. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 49 (1995), S. 81-85 
    ISSN: 1432-1041
    Keywords: Isoxazolyl penicillins ; Adverse drug reaction reporting ; jaundice ; drug-induced hepatitis ; flucloxacillin ; dicloxacillin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The clinico-pathological entity of flucloxacillin-associated cholestatic hepatitis is described and the recognition and documentation of cholestasis associated with flucloxacillin and with related isoxazolyl-penicillins (cloxacillin, dicloxacillin) is examined on an international basis, with particular reference to Australia. Data were obtained from the literature, from the Australian adverse drug reaction monitoring agency and from the Collaborative Centre for International Drug Monitoring (World Health Organisation) in Sweden. Approximately 600 cases of flucloxacillin-associated cholestatic hepatitis were collected, as well as 164 cases associated with other isoxazolyl penicillins. Jaundice and pruritus may first appear several weeks after administration of the drug has ceased and typically are severe and protracted. Liver tests may be abnormal for months after symptomatic recovery. Death is uncommon. Liver pathology shows centrizonal bile stasis with portal tract inflammation and variable loss of bile ducts. Approximately 1 in 15,000 users of flucloxacillin will develop the reaction. Increasing age (〉55 years) and prolonged intake (〉14 days) are particular risk factors. Cholestasis associated with cloxacillin/dicloxacillin appears to be similar in nature but is less well defined. Recognition and reporting of the reaction have been uncommon in the United Kingdom inter alia and high in Sweden and Australia, although estimates of risk have been similar. In Australia, the remarkably high rate of reports appears to be the result of sustained publicity for the reaction. There is only a trickle of reports of cholestatic hepatitis in association with the use of cloxacillin and dicloxacillin from the USA and Canada. The high level of awareness of the reaction and consequential regulatory action so far have not resulted in a diminution of its occurrence in Australia.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    International journal of infrared and millimeter waves 5 (1984), S. 301-314 
    ISSN: 1572-9559
    Keywords: submillimeter heterodyne receiver ; open structure mixer ; Schottky barrier diode ; HCOOH- ; HCOOD-laser
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The performance of a submillimeter heterodyne receiver using an HCOOH laser local oscillator and an open structure mixer with a Schottky barrier diode has been optimized for 693 GHz. Working at room temperature a single sideband (SSB) system noise temperature of 7,300 K, a mixer noise temperature of 6,100 K and a conversion loss of 12 dB has been achieved. The same receiver system has been investigated at 324 GHz using an HCOOD laser local oscillator yielding a noise temperature of 3,100 K (SSB), a mixer noise temperature of 2,400 K (SSB) and a conversion loss of 10 dB (SSB). An acousto-optical spectrometer has also been constructed, with 1024 channels and a channel-bandwidth of 250 kHz. The system NEP per channel was 2.5×10−17 W/Hz1/2 at 324 GHz and 5.0×10−17 W/Hz1/2 at 693 GHz.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1572-9559
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The properties of GaAs Schottky barrier diodes as video detectors and mixing elements were investigated in the frequency range from 0.8–2.5 THz. For the most sensitive diode, the video responsivity and system noise temperature were measured as a function of incident laser power. The highest video responsivity was 2,000 V/W at 214μm and 60 V/W at 118μm. For five diodes differing in doping, capacitance, series resistance and anode diameter, the system noise temperature was measured at 214μm and 118μm. The best single sideband (SSB) values are 12,300 K and 24,200 K at 214μm and 118μm, respectively. The system noise temperature versus frequency is given over the range from 0.5–3 THz for two specific diodes demonstrating that the sharpness of the I–V characteristics is only of secondary importance for mixer perfomance at such high frequencies.
    Type of Medium: Electronic Resource
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