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  • 1
    Electronic Resource
    Electronic Resource
    Optical characterization of Si-doped InAs1−xSbx grown on GaAs and GaAs-coated Si by molecular-beam epitaxy (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 2536-2542 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial layers of Si-doped InAs1−xSbx have been grown by molecular-beam epitaxy on GaAs and GaAs-coated Si substrates. The absorption coefficient was measured in the 3–12 μm wavelength range and the experimental data was fit using an analytical expression that was derived from the Kane band model. The fitted value of the Fermi level was used to calculate the electron concentration and the results were compared with doping levels obtained from secondary ion mass spectroscopy and Hall measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348694
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  • 2
    Electronic Resource
    Electronic Resource
    Preparation of hydrogenated amorphous silicon with tunable gap by homogeneous chemical vapor deposition (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 143-155 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This paper reports on the properties of doped and undoped amorphous silicon films deposited by the homogeneous chemical vapor deposition (HOMOCVD) technique. It is shown that good quality films can be grown at reasonable deposition rates of 100–150 A(ring)/min. It is also shown that in this growth regime, the main precursor is Si2H4, shifting to SiH2 at higher H2 dilution. The real limit for the growth rate is set by the phenomena of homogeneous and local nucleation. The optical band gap of undoped films deposited at these high growth rates, changes from 2.6 eV for a substrate temperature of 20 °C down to 1.6 eV at 280 °C. Very conductive B-doped HOMOCVD amorphous silicon films with tunable band gap can be obtained. This is very important for the use of such films for window layers in photovoltaic applications as an alternative to siliconcarbide. At a substrate temperature of 40 °C films were obtained with an optical gap of 2.34 eV and a room-temperature dark conductivity of 1.6×10−5/Ω cm. Down to a thickness of 100 A(ring), no thickness dependence of the dark conductivity has been observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347106
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  • 3
    Electronic Resource
    Electronic Resource
    Energy of arrays of nonperiodic interacting dislocations in semiconductor strained epilayers: Implications for strain relaxation (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 1773-1780 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The interaction energy EirrI of arrays of dislocations with nonperiodic (or irregular) distribution is calculated. The calculations have been made for uniform-random and Gaussian distributions of dislocations. The method used is, however, general and can also be applied to any arbitrary or an observed distribution of dislocations. The results for several values of average spacing p¯ and standard deviation σ are given and are compared with the energy EI of periodic arrays with spacing p=p¯. The total energy EirrT of strained layers containing nonperiodic dislocation arrays is also calculated. The results for both 90° and 60° dislocations are given. For sufficiently large numbers of dislocations, EirrI is always larger than EI. The difference between the energies EirrI and EI increases rapidly as the standard deviation σ of the nonperiodic distribution increases. The equilibrium strain relaxation in thick layers and the strain relaxation on annealing the metastable layers are usually calculated by modeling the nonperiodic array as an equivalent periodic array with p=p¯. It is found that this procedure for the calculation of the strain relaxation is not valid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353213
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  • 4
    Electronic Resource
    Electronic Resource
    Theory of the junction capacitance of an abrupt diode (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 4203-4211 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new theory for the junction capacitance of mathematically abrupt diodes is presented. In contrast with previous theories, Fermi–Dirac statistics are applied, and instead of using a parabolic density of states, a more appropriate function can be taken into account as this is required for heavily doped material. The main approximation is that of constant quasi-Fermi levels. Besides the study of symmetrical junctions, the behavior of asymmetrical abrupt junctions is both analyzed and explained. Anomalies resulting from the calculations are shown to be due to the mathematical discontinuity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344957
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  • 5
    Electronic Resource
    Electronic Resource
    Breakdown of global coupling in oscillatory chemical reactions (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 8668-8671 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The effects of global coupling through the gas phase in oscillatory surface chemical reactions are investigated using a model which represents the complex Ginzburg–Landau equation with an additional integral term. Depending on the parameters of the model, global coupling is found to have either a synchronizing or desynchronizing effect. Respectively, the breakdown of global coupling requires the presence of strong supercritical inhomogeneities or spontaneously occurs in a uniform system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465590
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  • 6
    Electronic Resource
    Electronic Resource
    Glucokinase and Fructokinase of Trichomonas vaginalis and Tritrichomonas foetus (1990)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 37 (1990), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Trichomonas vaginalis and Tritrichomonas foetus contain glucokinase and not a hexokinase of broad hexose specificity. Tritrichomonas foetus also contains a specific fructokinase which could be resolved from glucokinase by anion exchange chromatography. Native T. vaginalis glucokinase had a Mr of 76,000, and SDS-PAG electrophoresis showed two equally stained bands corresponding to Mr 40,000 and 38,000. Glucose and ATP were by far the best substrates for both trichomonad glucokinases, with Km values as low as 33–35 μM and 75–83 μM, respectively. Substrate saturation curves for these enzymes were all hyperbolic. Tritrichomonas foetus fructokinase required fructose and ATP, with Km values of 200 μM and 81 μM. None of the activities was affected by a number of potential regulatory metabolites, including glucose-6-phosphate. The only exception was AMP which in supraphysiological concentrations had an inhibitory effect on T. foetus fructokinase. In conclusion, the absence of regulation at the hexose phosphorylation step described here, as well as the presence of an easily reversible PPi: fructose-6-phosphate 1 -phosphotransferase described previously (Mertens, E., Van Schaftingen, E. & Müller, M. 1989. Mol. Biochem. Parasitol., 37:183–190), suggest that the rate of the 1st part of glycolysis in trichomonads is controlled only by the intracellular availability of hexoses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1990.tb01161.x
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  • 7
    Electronic Resource
    Electronic Resource
    Growth and structural characterization of embedded InAsSb on GaAs-coated patterned silicon by molecular beam epitaxy (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 928-930 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The molecular beam epitaxial growth of InAsSb on GaAs-coated patterned Si substrates is reported. The epilayers are grown embedded in wells so a coplanar Si-InAsSb surface can be obtained. The InAsSb epilayer morphology is compared for different substrate conditions (Si−well, Si−mesa, GaAs) using Nomarski contrast microscopy. High-voltage electron microscopy shows that the threading defect density of the InAsSb layers is high but decreases with thickness. In the reduced area electron diffraction pattern of the GaAs-InAsSb interface, additional diffraction spots are visible due to microtwins in the InAsSb. High-resolution electron microscopy reveals a regular array of misfit dislocations relieving the 14.2% lattice mismatch in the early stage of growth. Stripping Hall measurements for InAs0.05Sb0.95 show a constant mobility as a function of depth for the top 2 μm of the film and the 300 and 77 K mobility values are comparable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104480
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  • 8
    Electronic Resource
    Electronic Resource
    Influences of trace metal impurities on the thermal quenching of photoluminescence in hydrogenated amorphous silicon by homogeneous chemical vapor deposition (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1591-1593 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of trace metal impurities of low-temperature undoped amorphous silicon by homogeneous chemical vapor deposited a-Si:H has been explored for the first time. The metal impurities Ni, Cr, and Fe cause a shift of the transition temperature for the double-activated regime to a relatively low value. However, Ga and B impurities quench the photoluminescence intensity at a low temperature. Both of them cause weak photoemission of the films at room temperature. The shift of the transition temperature can be explained by the presence of non-radiative deep recombination centers. The quenching of the photoluminescence intensity is caused by the presence of nonradiative recombination centers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103137
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  • 9
    Electronic Resource
    Electronic Resource
    Magneto-optical investigation of flux penetration in Y1Ba2Cu3O7 thin films (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 1067-1069 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using the magneto-optical Faraday effect the magnetic flux penetration into high Tc superconducting Y1Ba2Cu3O7 thin films is investigated. Epitaxially grown high quality films (Tc(approximately-greater-than)88 K, jc(approximately-greater-than)106 A/cm2 at 77 K) show a flux penetration in three steps, the formation of a flux front if the acting magnetic field reaches Hc1 at the edge of the specimen, the movement of the flux front towards the center of the sample, and the increase of the flux density after the flux front reaches the center. The remanent state shows trapped magnetic flux in the film, indicating inhomogeneously distributed pinning centers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104283
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  • 10
    Electronic Resource
    Electronic Resource
    Polycrystalline silicon solar cells with a mechanically formed texturization (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 2941-2943 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polycrystalline (Wacker SILSO) silicon has been mechanically textured using a conventional dicing saw and beveled blades for V-groove formation. The minimum optical reflectivity achievable is limited by the blade tip radius and surface roughness after damage etching. Solar cells were prepared using a conventional diffusion and screen printed metallization. Grooved cells without an additional antireflection coating (jsc=31.8 mA/cm2, Voc=536 mV, FF=69%, η=11.8%) showed a 20% increase in jsc and a 1.1% absolute efficiency improvement as compared to a nongrooved reference cell with an antireflexion coating (jsc=26.4 mA/cm2, Voc=547 mV, FF=74.1%, η=10.7%). In grooved cells the efficiency is found to be limited mainly by the fill factor due to a nonoptimized front grid design.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.109628
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