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  • 1
    Electronic Resource
    Electronic Resource
    GaAs surface reconstruction obtained using a dry process (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2035-2037 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report attaining Ga-terminated (4×2) surface reconstruction on virgin GaAs substrates using a completely dry process at temperatures below the oxide sublimation temperature and without group V overpressure. The native oxides are removed with an electron cyclotron resonance hydrogen plasma treatment, followed by annealing at 500 °C in ultrahigh vacuum, which yields a reconstructed surface suitable for epitaxial overgrowth. Characterization by secondary ion mass spectroscopy and transmission electron microscopy reveals the complete removal of O, reduced C, and high structural order at the epilayer/substrate interface when this preparation method is used before molecular beam epitaxy. Annealing the substrate at a lower temperature yields a nonreconstructed surface possessing significant impurity concentrations, and leads to dislocation defects at the epilayer/substrate interface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353148
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Hydrogen plasma removal of AlGaAs oxides before molecular beam epitaxy (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 735-737 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a method for the removal of AlxGa1−xAs native oxides for 0≤x≤1, prior to molecular beam epitaxial overgrowth. The oxides formed on epilayers of AlGaAs after atmospheric exposure are removed in an electron cyclotron resonance hydrogen plasma with a substrate temperature less than 400 °C. Reflection high energy electron diffraction indicates the plasma-prepared AlGaAs surface are oxide-free and crystalline; after a vacuum anneal to 250–500 °C, GaAs or AlGaAs are epitaxially overgrown on these surfaces. Secondary ion mass spectroscopy detects C, O, and Si impurities at the interfaces, where their concentrations increase with increasing Al content of the exposed surface. The quality of the interface and the overgrown film, as observed by transmission electron microscopy, are found to be better for lower interface impurity densities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108854
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Molecular beam epitaxial regrowth on in situ plasma-etched AlAs/AlGaAs heterostructures (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 1738-1740 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial regrowth by solid-source molecular beam epitaxy (MBE) on dry etched heterostructures possessing exposed AlAs surfaces is accomplished for the first time using a vacuum integrated processing. Samples composed of multilayers of AlAs and AlGaAs are patterned with a SiO2 mask and are anisotropically etched using a low damage electron cyclotron resonance (ECR) SiCl4 plasma process. Etched samples are transferred in ultrahigh vacuum between the ECR and MBE chambers to avoid atmospheric exposure before regrowth. Microstructural analysis of the overgrown layers by scanning and transmission electron microscopy indicates that epitaxial regrowth on both the etched field and vertical sidewalls is achieved. The regrown material is found to contain microtwin plates, but few dislocations, indicating the good quality of the overgrowth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107202
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Removal of GaAs surface contaminants using H2 electron cyclotron resonance plasma treatment followed by Cl2 chemical etching (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 2658-2660 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a novel dry process to remove the surface contaminants C, Si, and O from GaAs substrates. This method utilizes an electron cyclotron resonance hydrogen plasma to remove the native oxides, followed by a very brief Cl2 chemical etching of GaAs to further reduce C and Si residues, and a final vacuum anneal. Characterization by secondary ion-mass spectrometry (SIMS) typically reveals the removal of C, Si, and O at the overgrown/processed interface to the levels below the SIMS detection limit. The as-processed GaAs surface, a Ga-stabilized reconstructed (4×6), is atomically smooth, and is as clean as a surface of freshly grown GaAs epilayers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.109277
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    The acute effects of intravenous isosorbide dinitrate during cardiac surgery (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Anaesthesia 42 (1987), S. 0 
    Details
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The acute effects of intravenous isosorbide dinitrate during open heart surgery were studied in 15 adult patients. Consistent and significant (p 〈 0.001) reductions in pulmonary vascular resistance (25% before. 23% after, cardiopulmonary bypass) and mean pulmonary artery pressure (14% before, 13% after, cardiopulmonary bypass) were observed in the absence of significant changes in cardiac index, mean systemic arterial pressures or right or left atrial filling pressures. These findings indicate that after cardiopulmonary bypass, when right ventricular dysfunction with raised pulmonary vascular resistance may occur, selective reduction of right ventricular afterload with isosorbide dinitrate may prove beneficial.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2044.1987.tb04041.x
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    Paper (German National Licenses)
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