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  • 1990-1994  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Channel adjustments to reservoir construction and gravel extraction along Stony Creek, California (1993)
    Springer
    Environmental geology 21 (1993), S. 256-269 
    Details
    ISSN: 1432-0495
    Keywords: Instream gravel extraction ; Channel incision ; Downstream effects of reservoirs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Stony Creek (drainage area 1920 km2), a tributary to the Sacramento River 200 km north of San Francisco, has experienced channel adjustments to both dam construction and instream gravel extraction. Black Butte Dam, constructed in 1963, reduced flood peaks and trapped the annual 100,000 m3 of bedload sediment formerly delivered from the upper watershed. The reach below the dam changed from an active braided channel to an incised, single-thread channel shortly after dam construction. About 25 km downstream of the dam, large instream gravel mines annually extract 230,000–580,000 m{su3} and have induced channel incision of over 5 m, necessitating bridge repairs costing US$1.4 million.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00775916
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Transition between Ge segregation and trapping during high-pressure oxidation of GexSi1−x/Si (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 4750-4755 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A transition from Ge segregation to trapping during high-pressure oxidation of GexSi1−x alloys has been observed. The atomic fraction x of Ge was varied from 0.4% to 26%, and oxidations were performed at 740 °C under 102 atm of dry O2. It was observed that the effect of oxidation on the Ge distribution could be divided into three stages. In the initial stage of the oxidation, Ge was segregated from the growing oxide and accumulated in a Ge-rich layer at the oxide/alloy interface. For alloys with high Ge content this initial stage was very short. In the second stage of oxidation, after a critical quantity of Ge had accumulated at the interface, there was a transition from segregation to trapping of Ge in the oxide. In the third stage, the critical amount of Ge remained segregated at the interface, and the final oxide layer was Ge free. A kinetic model based on a steady-state equilibrium between the diffusive flux of Si across the Ge-rich layer and the rate of Si consumption by the oxidation reaction predicts, with reasonable agreement, the critical quantity of segregated Ge for the onset of trapping.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354345
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Orientation of the electric-field gradient arising from a vacancy in Hg0.79Cd0.21Te (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 4943-4947 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have used the perturbed angular correlation technique to measure the orientation of the electric-field gradients (EFGs) due to vacancy trapping by substitutional indium donors in the II-VI semiconductor Hg0.79Cd0.2Te. Previously, two hyperfine interaction frequencies were measured and were attributed to the trapping of a metal vacancy at a next nearest-neighbor site to the indium atom in bulk solid-state recrystallized materials. In the present experiments, measurements are done on thin-film samples to find the principal axes of the EFGs. Both EFGs are found to have principal axes parallel to a 〈111〉 crystal axis, despite the fact that a simple point charge model supports a 〈110〉 EFG for this 〈110〉-oriented In-VHg complex. A similar situation exists for indium-vacancy pairing in other II-VI semiconductors. We propose that the 〈111〉 EFG orientation arises from the electric dipole moments of the highly polarized Te ions in the region of the vacancy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354331
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Indium-Hg vacancy interactions in Hg1−xCdxTe measured by perturbed angular correlation (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 938-940 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The interaction of mercury vacancies with dopant indium atoms in Hg0.79Cd0.21Te was studied using the perturbed γγ angular correlation (PAC) technique. Two dominant PAC signals, characterized by quadrupole interaction strengths νQ1=83 MHz and νQ2= 91 MHz and asymmetry parameters η1=η2=0.08, were observed and attributed to one or more In-VHg complexes. The complexes appeared after annealing doped samples at T≥350 °C in vacuum and quenching. The fraction of In atoms associated with vacancies was increased further by annealing at 80 °C for (approximately-greater-than)10 h. The In-vacancy complexes vanished on annealing in a Hg-saturated atmosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106307
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Single-crystal diamond plate liftoff achieved by ion implantation and subsequent annealing (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 3124-3126 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe a new method for removing thin, large area sheets of diamond from bulk or homoepitaxial diamond crystals. This method consists of an ion implantation step, followed by a selective etching procedure. High energy (4–5 MeV) implantation of carbon or oxygen ions creates a well-defined layer of damaged diamond that is buried at a controlled depth below the surface. For C implantations, this layer is graphitized by annealing in vacuum, and then etched in either an acid solution, or by heating at 550–600 °C in oxygen. This process successfully lifts off the diamond plate above the graphite layer. For O implantations of a suitable dose (3×1017 cm−2 or greater), the liftoff is achieved by annealing in vacuum or flowing oxygen. In this case, the O required for etching of the graphitic layer is also supplied internally by the implantation. This liftoff method, combined with well-established homoepitaxial growth processes, has considerable potential for the fabrication of large area single crystalline diamond sheets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107981
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    Paper (German National Licenses)
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