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  • 1
    Electronic Resource
    Electronic Resource
    Solubilization and Characterization of σ-Receptors from Guinea Pig Brain Membranes (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 53 (1989), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The σ-receptor, a distinct binding site in brain tissue that may mediate some of the psychotomimetic properties of benzomorphan opiates and phencyclidine, has been sol-ubilized using the ionic detergent sodium cholate. Binding assays were performed with the solubilized receptor using vacuum filtration over polyethyleneimine-treated glass fiber filters. The pharmacological specificity of the solubilized binding site for σ-receptor ligands is nearly identical to the membrane-bound form of the receptor, with the order of potencies for displacement of the selective σ-ligand [3H]di-o-tolylguanidine ([3H]DTG) closely correlated. The stereoselectivity for (+)-benzomorphan opiate enantiomers was retained by the solubilized receptor. The soluble receptor retained high affinity for binding of [3H]DTG (KD= 28 ± 0.5 nM) and (+)-[3H]3-(3-hydroxyphenyl)-N-(l-propyl)piperi-dine {(+)-[3H]3-PPP} (KD= 36 ± 2 nM). Photoaffinity labeling of the solubilized receptor by [3H]p-azido-DTG, a σ-selective photoaffinity label, resulted in labeling of a 29-kilodalton polypeptide identical in size to that labeled in intact membranes. Estimation of the Stokes radius of the [3H]DTG binding site was obtained by Sepharose CL-6B chromatography in the presence of 20 mM cholate and calculated to be 8.7 nm. This value was identical to the molecular size found for the binding sites of the σ-selective ligands (+)-[3H]3-PPP and (+)-[3H]SKF-10,047, supporting the hypothesis that all three ligands bind to the same macro-molecular complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1989.tb08554.x
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  • 2
    Electronic Resource
    Electronic Resource
    Origin of n-type conductivity of low-temperature grown InP (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 600-602 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is shown with correlated magnetic resonance and electrical measurements that the PIn antisite is the prevailing defect in InP grown by molecular-beam epitaxy at low temperature. The first ionization level of the PIn antisite is resonant with the conduction band, which makes the material n-type conducting due to autoionization of the PIn antisite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357052
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  • 3
    Electronic Resource
    Electronic Resource
    Homoepitaxial growth of GaN using molecular beam epitaxy (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 2195-2198 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this article, experimental results are presented for the homoepitaxial deposition of a GaN overlayer onto a bulk single-crystal GaN substrate using molecular beam epitaxy. Transmission electron microscopy shows a superior structural quality of the deposited GaN overlayer when compared to heteroepitaxially grown layers. Photoluminescence shows narrow excitonic emission (3.467 eV) and the very weak yellow luminescence, whereas the bulk substrate luminescence is dominated by this deep level emission. These results show that homoepitaxy of GaN can be used to establish benchmark values for the optoelectronic properties of GaN thin films. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363112
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of low-temperature AlxGa1−xAs lattice properties using high resolution x-ray diffraction (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 4452-4454 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using high resolution x-ray diffraction techniques, we have studied the lattice parameter behavior of low-temperature (LT) AlxGa1−xAs as a function of annealing temperature and aluminum content. Similar to LT GaAs, the as-grown LT AlxGa1−xAs layers exhibit a dilated lattice constant which, upon annealing, contracts to that of "normal'' material. The onset of this contraction in LT Al0.3Ga0.7As, however, is found to occur at an annealing temperature nearly 100 °C higher than that required for LT GaAs. In addition, the relative lattice expansion in the as-grown LT layer is found to be a decreasing function of Al content, ranging from 0.099% for LT GaAs to 0.059% for LT Al0.3Ga0.7As. This is attributed to lower than expected As incorporation in the LT AlxGa1−xAs during growth. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359473
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  • 5
    Electronic Resource
    Electronic Resource
    Annealing dynamics of arsenic-rich GaAs formed by ion implantation (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 1470-1475 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the annealing temperature dependence of structural and electrical properties in heavily arsenic implanted GaAs which has a similar amount of excess arsenic to low temperature GaAs (LT-GaAs). The fundamental properties of this material are quite similar to those of LT-GaAs. High resolution x-ray diffraction measurements have revealed that it has an increased lattice constant, which is reduced to the value of bulk GaAs by annealing between 300 and 400 °C. Electrical conduction in this material is dominated by hopping between deep states, which is also reduced by annealing above 350 °C. In samples annealed at temperatures ranging from 600 to 850 °C, the dominant electron trap is EL2; it has been confirmed by resistivity measurements with n-i-n structures that the Fermi level is pinned by EL2. In samples annealed below 500 °C, the dominant electron trap is not EL2 but the U-band, although electron paramagnetic resonance measurements show the existence of a large concentration of the ionized arsenic antisite defect (AsGa+). This supports the notion that the U-band is formed by AsGa defects with slightly modified carrier emission properties compared with EL2. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360235
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  • 6
    Electronic Resource
    Electronic Resource
    Liquid-Liquid Extraction between Rotating Concentric Cylinders (1960)
    s.l. : American Chemical Society
    Industrial & engineering chemistry 52 (1960), S. 929-934 
    Details
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ie50611a027
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  • 7
    Electronic Resource
    Electronic Resource
    The formation of a continuous amorphous layer by room-temperature implantation of boron into silicon (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 1414-1418 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ion implantation of 60 keV boron into {100} silicon at medium beam currents (150 μA) was performed at 300–315 K over the dose range from 1 to 8×1016/cm2. Diffraction contrast and high-resolution phase contrast transmission electron microscopy (TEM) were used on plan-view and 90° cross-section samples to study the formation of a continuous amorphous layer as a function of increasing dose. Our TEM results show that, unlike implantation of Si with heavier ions where amorphization initially occurs at or around the projected range, the amorphization by high dose (〉5×1016/cm2) B+-implanted Si first occurs at and/or near the surface. It is proposed that the buildup of a high concentration of vacancies which inevitably occurs near the surface during high-dose B+ implantation is primarily responsible for the observed near-surface amorphization. Based on the results of this investigation and those available in the published literature, it appears that low temperature (slow recombination rate for point defects) and high beam current (high generation rate for point defects) implantation may result in the optimum conditions for amorphous layer formation with boron.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341122
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  • 8
    Electronic Resource
    Electronic Resource
    Enhanced elimination of implantation damage upon exceeding the solid solubility (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 4114-4117 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Implantation of silicon wafers with Ga and P, under specific conditions, results in enhanced category-II (end of range) dislocation loop elimination after short thermal cycling. Comparison of these results with transmission electron microscopy studies of Si-, Ge-, As-, Al-, and Sb-implanted samples indicate that the enhanced elimination process occurs only when the peak of the impurity concentration exceeds the solid solubility of the impurity in silicon at the annealing temperature and the resulting precipitates are dissolving. The activation energy for enhanced elimination of these extrinsic catetory-II dislocation loops is shown to be 5±0.5 eV. It is proposed that vacancy emission by the dissolving precipitates is responsible for the enhanced elimination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339126
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  • 9
    Electronic Resource
    Electronic Resource
    Mechanism for nearly ohmic behavior in annealed Au/n-GaAs Schottky diodes (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 711-715 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The origin of the ohmic behavior observed after annealing Au/n-GaAs {110} Schottky diodes was investigated by electron-beam-induced current (EBIC) measurements of diode plan views and cross sections, combined with standard scanning electron microscopy and transmission electron microscopy techniques. The large leakage currents responsible for this behavior arise at the periphery of the deposited gold films, where elongated gold crystallites which lie on the GaAs surface are observed after heat treatment. These crystallites are typically 2–5 μm long, 500–2000 A(ring) wide, and are crystallographically oriented along the GaAs [110] direction. EBIC imaging demonstrated that a space-charge region was present under the peripheral area showing the gold crystallites. Comparison of current collection as measured with EBIC between annealed and unannealed diodes shows a large reduction in current collection under and around the periphery of the annealed diodes. These data allow attribution of the ohmic behavior to a recombination current. Experiments done with overlapping Au evaporations show that recombination on the bare GaAs surface between the observed crystallites surrounding each annealed diode is the main component of this recombination current, and thus of the large leakage current.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343543
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  • 10
    Electronic Resource
    Electronic Resource
    Transmission electron microscopy investigation of dislocation bending by GaAsP/GaAs strained-layer superlattices on heteroepitaxial GaAs/Si (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 5115-5118 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A systematic study, investigating the effects of strained-layer superlattices (SLSs) on threading dislocations present in GaAs/Si heteroepitaxial layers, was conducted. Transmission electron microscope contrast analysis was performed on ∼1% lattice-mismatched GaAs0.72P0.28/GaAs SLSs grown on GaAs/Si substrates.Threading dislocations were found to have Burgers vectors inclined to the GaAs/Si interface. Individual strained layers ranging in thickness from 100 to 250 A(ring) were observed to have negligible effect on dislocation bending. Instead, dislocation bending occurred primarily at the first and last interfaces of the SLS packets. Similarly, effective dislocation bending was observed using 1000 A(ring) layers. Threading dislocation density close to the GaAs/Si heterointerface was found to depend on the SLS packet proximity to the interface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347049
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