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  • 1
    Electronic Resource
    Electronic Resource
    Semi-insulating GaAs: A possible substrate for a field-assisted positron moderator (1994)
    Springer
    Applied physics 59 (1994), S. 259-273 
    Details
    ISSN: 1432-0630
    Keywords: 78.70.Bj ; 79.90 ; 72.20.Ht
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Positron lifetime spectroscopy measurements have been carried out for semi-insulating GaAs with applied electric fields in the samples directed towards, and away from the positron injecting contact. The lifetime spectra have been decomposed into two components, the longer of which (≈400 ps) is characteristic of open volume defects at the metal-semiconductor interface through which positrons are injected. The interesting feature of these experiments is the large increase in the intensity of this interface component as the field is directed towards the contact. We show that this increase is caused by a significant fraction of implanted positrons drifting under the influence of a strong electric field produced by a layer of space-charge formed adjacent to the positron injecting contact. The general trend of the intensity variation is well explained by the proposed model. Experiments involving the application of an ac bias to the samples strengthen the suggestion that the space charge region is largely formed from ionized EL2 donors. The results of the present work indicate that semi-insulating GaAs possesses properties that make it a suitable material for the fabrication of a high efficiency (≈10%) room-temperature field-assisted positron moderator. The extraction of positrons from the GaAs substrate into the vacuum through a thin metalization is discussed based upon available positron affinities for the GaAs and various elemental metals. These data suggest that a few monolayers of a strongly electronegative metal such as Au or Pd may allow vacuum emission through quantum tunneling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00348229
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  • 2
    Electronic Resource
    Electronic Resource
    A systematic approach to the measurement of ideality factor, series resistance, and barrier height for Schottky diodes (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 4739-4742 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A nongraphical approach is proposed for measuring and evaluating the ideality n factor and the series resistance of a Schottky diode. The approach involves the use of an auxiliary function and a computer-fitting routine. This technique has been found to be both accurate and reliable. The validity of this has also been confirmed by way of I-V measurements using both commercially available and laboratory-prepared Schottky diodes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352082
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  • 3
    Electronic Resource
    Electronic Resource
    Limits to ion energy control in high density glow discharges: Measurement of absolute metastable ion concentrations (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 7188-7194 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Unprecedented demands for uniformity, throughput, anisotropy, and damage control in submicron pattern transfer are spurring development of new, low pressure, high charge density plasma reactors. Wafer biasing, independent of plasma production in these new systems is intended to provide improved ion flux and energy control so that selectivity can be optimized and damage can be minimized. However, as we show here, an inherent property of such discharges is the generation of significant densities of excited, metastable ionic states that can bombard workpiece surfaces with higher translational and internal energy. Absolute metastable ion densities are measured using the technique of self-absorption, while the corresponding velocity distributions and density scaling with pressure and electron density are measured using laser-induced fluorescence. For a low pressure, helicon-wave excited plasma, the metastable ion flux is at least 24% of the total ion flux to device surfaces. Because the metastable ion density scales roughly as the reciprocal of the pressure and as the square of the electron density, the metastable flux is largest in low pressure, high charge density plasmas. This metastable ion energy flux effectively limits ion energy and flux control in these plasma reactors, but the consequences for etching and deposition of thin films depend on the material system and remain an open question.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352391
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  • 4
    Electronic Resource
    Electronic Resource
    Comparison of propagation loss of sine-generated and constant radius S bends in Al(Ga)As waveguides (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 730-731 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Constant radius and sine-generated S bends were fabricated from double heterostructure Al(Ga)As waveguides. No significant difference in the loss characteristics between the two structures was observed. These results are within the bounds of our beam propagation method calculation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355240
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  • 5
    Electronic Resource
    Electronic Resource
    The development of an assay for resistance to Phytophthora cambivora in almond rootstocks using shoots excised from tissue cultures (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Plant pathology 41 (1992), S. 0 
    Details
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The pathogenicity of Phytophthora cambivora to Mission almond seedlings was confirmed by twig inoculation in situ. An excised twig assay using four isolates of P. cambivora showed almond cvs Mission and Chellaston to be susceptible, whereas peach cv. Nemaguard, which is commonly used as a rootstock for almond, was resistant. P. cambivora isolates 179 and 108, the most and least aggressive, respectively, were selected for further studies. The excised twig assay was modified for screening micropropagated shoots in vitro for response to P. cambivora. Defoliated shoots were placed upright in agar medium colonized with the fungus, and development of necrosis was assessed over a period of 2-3 days. Shoots of Chellaston developed extensive necrosis and those of Nemaguard developed little necrosis, whereas shoots of hybrid selections from peach x almond crosses were generally intermediate in response. This method permits rapid and efficient screening of large amounts of material, and would be a useful adjunct to conventional almond breeding programmes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3059.1992.tb02465.x
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  • 6
    Electronic Resource
    Electronic Resource
    Determination of leakage resistance of Schottky contacts by photovoltage measurements (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 7361-7364 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The leakage resistance of Schottky contacts has been determined from photovoltage measurements, thus allowing the contribution of the leakage current to the current transport in the Schottky contacts to be easily evaluated. It is found that under identical conditions of sample fabrication, different Schottky contacts have nearly the same leakage resistance. A comparison between a theoretical calculation and experimental data for the photocurrent-photovoltage relationship shows that the leakage current becomes dominant at low temperatures and small photocurrents. In these regimes, the current transport is dominated by the leakage current, and as a result, a linear relation (the Ohmic rule) between the photocurrent and the photovoltage is observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356649
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  • 7
    Electronic Resource
    Electronic Resource
    An environmental cell transmission electron microscope (1991)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 1438-1444 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An aperture-limited, differentially pumped environmental cell has been developed and installed in a JEOL 4000 EX electron microscope. With this environmental cell it is possible to observe, at high spatial resolution, the detailed changes in microstructure that occur during the interaction between a solid and a gaseous environment. The cell has been pressurized to 70 Torr with H2 gas for several hours with no adverse effects on the microscope performance. While the initial tests have been performed with hydrogen gas, the materials used to construct the environmental cell can tolerate corrosive environments. The key features of the environmental cell design along with the results from some applications are presented in this paper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142464
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  • 8
    Electronic Resource
    Electronic Resource
    Diagnostics of high density plasma reactors used in the processing of electronic and photonic materials (invited) (abstract) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4920-4920 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: High-density plasmas are being used in the manufacture of electronic devices and systems because they provide high throughput at low pressure and low ion energy. Low pressure is desirable for maximizing process uniformity over large substrates while low ion energy is desirable for minimizing process-induced damage. However, the optimal design for a high density plasma reactor is unclear and the technology has largely developed empirically: many alternatives for magnetic and geometric design are offered for the same processing applications. In this talk we discuss diagnostic measurements of high density plasma reactors and how they can be used in developing improved reactor designs and in providing insight into materials processing. Laser-induced fluorescence measurements of metastable ion velocity distributions are made in both Ar and Cl2 electron cyclotron resonance and helicon plasmas. The effects of magnetic field configuration, power, and pressure on the energy and angular distributions of the ions will be described along with electron density measurements made by microwave interferometry. Where appropriate, comparisons will be made with the recent theoretical results of Graves and Porteous [D. B. Graves and R. K. Porteous, American Vacuum Society National Symposium, Seattle, WA, November (1991)].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143548
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  • 9
    Electronic Resource
    Electronic Resource
    Optimization of the Freezing Conditions on Mackerel and Amberfish for Manufacturing Minced Fish (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 50 (1985), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Optimal freezing, frozen storage and thawing conditions in preserving mackerel and amberfish for producing minced fish products were investigated. Based on assessments of extractability of 0.6M KCl-soluble proteins and actomyosin, Ca-ATPase activity of actomyosin, and gel-forming ability of kamaboko (kind of minced fish meat product), semi-dressed, dressed, and filleted samples showed stable and good quality of gel-forming ability during 3 months storage at −20°C. Optimal ultimate freezing temperatures of mackerel and amberfish were −20°C and between −30°C and −40°C, respectively. The optimal storage temperatures for mackerel and amberfish were −20°C and −40°C, respectively. Appropriate thawing methods for frozen mackerel were microwave and 20°C running water defrosting, while those for frozen amberfish were microwave, 20°C running water, and room temperature defrosting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1985.tb13783.x
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  • 10
    Electronic Resource
    Electronic Resource
    Posttreatment with sodium arsenite is coclastogenic in log phase but not in stationary phase (1987)
    Springer
    Human genetics 〈Berlin〉 75 (1987), S. 159-162 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Posttreatment with sodium arsenite in log phase synergistically increases the chromosomal aberrations induced by ethyl methanesulfonate in Chinese hamster ovary cells, human fibroblasts, and human lymphocytes. However, posttreatment with sodium arsenite in stationary phase has no apparent effect on the clastogenicity of ethyl methanesulfonate. These results indicate that the cycling state of the cell plays a crucial role in the action of arsenite coclastogenicity. One prediction from this finding is that in combined treatment, posttreatment with sodium arsenite should preferentially kill cancer cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00591079
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