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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 55 (1983), S. 2382-2387 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    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 73 (1993), S. 7851-7856 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Heavily carbon-doped GaAs (1×1018∼1×1020 cm−3) grown by low-pressure metalorganic chemical vapor deposition using triethylgallium and arsine as sources and liquid carbon-tetrachloride (CCl4) as dopant has been investigated. The carrier concentration was verified at various growth temperatures, V/III ratios, and CCl4 flow rates. Dopant concentration first increased from 550 °C and reached a maximum at 570 °C growth temperature (Tg) and then decreased monotonously. Carbon incorporation was strongly enhanced when the V/III ratio was less than 30 at Tg=590 °C or less than 40 at Tg=630 °C. Hole concentration increased and then decreased as CCl4 flow rate increased. Growth rate of layers decreased as growth temperature and flow rate of CCl4 increased. The doping efficiency of epitaxial layers grown on the (100) substrate was higher than that on the 2° off toward 〈110(approximately-greater-than) misoriented substrate. Carbon-doped GaAs films had higher Hall mobility than zinc-doped GaAs films at high doping levels due to less self-compensation. The highest dopant concentration in this system was 2.3×1020 cm−3 at Tg=580 °C and V/III=10.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 672-678 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have successfully grown In0.49Ga0.51P/GaAs heterostructures and made InGaP-based high electron mobility transistors (HEMTs) by low-pressure metalorganic chemical vapor deposition. We have found the epitaxial layer of InGaP with a Hall mobility of 4073 cm2/V s (300 K) and the photoluminescence full width at half-maximum of 1 meV (4.2 K) for GaAs, 12 meV (4.2 K) for In0.49Ga0.51P. Zinc-induced disordering phenomenon was examined by transmission electron microscope. By Shubnikov-de Haas measurement, we demonstrated the existence of a two-dimensional electron gas in InGaP/GaAs heterojunctions. The sheet carrier concentration of 2DEG is around 8.8×1011 cm−2 at 1.5 K. A HEMT device with 1 μm×40 μm gate (pattern) shows an extrinsic transconductance of 65.5 mS/mm and an intrinsic transconductance of 266 mS/mm at 300 K.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 7605-7606 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 4771-4776 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The far wing absorption profiles for excitation on the Ca(4s2 1S0–4s5p 1P01) atomic transition, broadened in collisions with He are measured. We observe strong absorption in both wings and a blue wing satellite near Δ∼125 cm−1. We tentatively identify this satellite as due to a maximum in the CaHe(4s2 1∑+–4s5p 1∑+) difference potential. These line-broadening techniques are used to study electronic energy transfer in the spin-changing collisions of Ca with He: Ca(5p 1P01) +He→Ca(5p 3P0J)+He+ΔE. Measurements of the "single collision'' triplet–singlet branching ratio as a function of laser detuning from the atomic resonance frequency indicate a clear red wing/blue wing asymmetry. We interpret this asymmetry in terms of a preferential orbital alignment effect in the energy transfer process [Phys. Rev. Lett. 53, 2296 (1984)]. No clear structure is observed in the range of detunings probed that might indicate the curve crossing responsible for the energy transfer.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 2210-2214 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low-temperature (20 K) luminescent properties of heavily carbon- and zinc-doped GaAs grown by low-pressure metalorganic chemical vapor deposition were investigated. The luminescence linewidth became broader at low temperatures when p(approximately-greater-than)4×1019 cm−3 due to the appearance of a shoulder peak. The main peak shifted to low energy when the dopant concentration was increased; however, the shoulder peak was at around 1.485 eV and was nearly independent of the dopant concentration. The peak of the band-to-acceptor transition occurred at low temperature and dominated the emission spectra of degenerate GaAs. The peak energy of Zn-doped samples was lower than that of C-doped samples because of the existence of defects. The excitation power intensity was varied to investigate the behavior of the shoulder peak for both types of dopants. The shoulder peak was a part of the main peak because of the recombination between the conduction band and the bottom of the impurity band.
    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 75 (1994), S. 5453-5455 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An anomalous mobility enhancement and metallic-type conductivity were observed in heavily carbon-doped GaAs grown by low-pressure metalorganic chemical vapor deposition. The 77 K mobility was slightly lower than that of 300 K for hole concentration between 1×1018 and 4×1018 cm−3. However, the 77 K mobility was enhanced from p(approximately-greater-than)4×1018 cm−3, and the 300 K mobility slowly decreased with increasing hole concentration that ranged from 7×1018 to 3×1019 cm−3. As a result, the 77 K mobility was around 50%–60% greater than the 300 K mobility due to the metallic-type conductivity.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 2313-2315 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The surface of ultrathin silicon on insulator (SOI) material has been characterized with surface science analysis techniques including atomic-resolution scanning tunneling microscopy. It is shown that the (100) SOI surface can be fabricated with a comparable degree of structural perfection as the (100) surface of bulk Si. Fermi level pinning by "type C" dimer defects results in a fully depleted and thus effectively insulating Si film. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 103-105 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Adhesion of Cu to Teflon has been studied by depositing Cu to Teflon with and without a presputtering prior to the Cu deposition. Without presputtering, a weak adhesion is observed, with a value of 1 g/mm, which fails the scotch tape test. With a presputtering using 500 eV Ar+ ions, the adhesion rapidly increases, becoming evident after a sputtering of 10 s, and reaches maximal increases of 50 times at longer sputtering times. All the Cu films deposited after presputtering show strong adhesion, and can only be removed by forceful scratching with sharp tools. The presputtering was shown to change both the surface morphology of Teflon, with the deposited Cu following the morphologies created, and the interface chemical bonding between Cu and Teflon as revealed by x-ray photoelectron spectroscopy. Exposure of the presputtered Teflon to air prior to the Cu deposition shows no effect on the strong adhesion obtained. An interface bonding model is suggested for the enhanced adhesion observed.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science, Ltd
    Clinical & experimental allergy 31 (2001), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The occurrence of asthma and allergy are related to lifestyle factors, and dietary pattern may be one of the contributing factors.To examine the possible association between dietary intake and the prevalence of asthma and allergic rhinitis in teenagers.In a population-based cross-sectional survey, the relationship was sought between food frequency and physician-diagnosed asthma and allergic rhinitis in 1166 adolescents aged 13–17.The prevalence was 4.0% for asthma and 12.4% for rhinitis. Living in an urbanized area was a significant predictor of asthma and rhinitis. In univariate analysis, higher frequencies of oily fish, butcher's meat, liver and deep-fried foods were associated with asthma. Relevant food frequency variables were dichotomized at the 75th percentile for multivariate logistic regression analysis, which included adjustment for two levels of urbanization. Asthma was associated with intakes of liver (OR = 2.32, 95%CI 1.11–4.80), deep-fried foods (OR = 2.13, 95%CI 1.06–4.30) and butcher's meat (OR 1.84, 95%CI 0.89–3.80). In a similar analysis, allergic rhinitis was associated with liver (OR = 1.67, 95%CI 1.06–2.63). No protective effect was demonstrated for any of the food items examined.Protein-rich and fat-rich foods of animal origin were associated with a higher prevalence of asthma in teenagers.
    Type of Medium: Electronic Resource
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