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  • 1
    Electronic Resource
    Electronic Resource
    Electron emission from pseudospark cathodes (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 1494-1502 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The pseudospark cathode has the remarkable property of macroscopically homogeneous electron emission at very high current density ((approximately-greater-than)1 kA/cm2) over a large area (some cm2). The model of electron emission presented here is based on the assumption that the pseudospark microscopically utilizes explosive arc processes, as distinct from earlier models of "anomalous emission in superdense glow discharges.'' Explosive emission similar to vacuum are cathode spots occurs rapidly when the field strength is sufficiently high. The plasma remains macroscopically homogeneous since the virtual plasma anode adapts to the cathode morphology so that the current is carried by a large number of homogeneously distributed cathode spots which are similar to "type 1'' and "type 2'' spots of vacuum arc discharges. The net cathode erosion is greatly reduced relative to "spark gap-type'' emission. At very high current levels, a transition to highly erosive spot types occurs, and this "arcing'' leads to a significant reduction in device lifetime. Assuming vacuum-arc-like cathode spots, the observed current density and time constants can be easily explained. The observed cathode erosion rate and pattern, recent fast-camera data, laser-induced fluorescence, and spectroscopic measurements support this approach. A new hypothesis is presented explaining current quenching at relatively low currents. From the point of view of electron emission, the "superdense glow'' or "superemissive phase'' of pseudosparks represents an arc and not a glow discharge even if no filamentation or "arcing'' is observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357724
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  • 2
    Electronic Resource
    Electronic Resource
    Two-dimensional numerical optimization study of the rear contact geometry of high-efficiency silicon solar cells (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 5391-5405 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Under one-sun illumination, the highest energy conversion efficiencies of silicon solar cells are presently obtained with bifacially contacted n+p cells, where contact to the p-type substrate is made via small openings in the rear passivating oxide. In this work, a state-of-the-art 2-dimensional (2D) semiconductor device simulator is applied to these devices in order to investigate the effects arising from the rear metallization scheme. The impact of various cell parameters [i.e., substrate resistivity, rear surface recombination model (flatband or surface band bending conditions), positive oxide charge density, capture cross section ratio] on the cell's current-voltage (I-V) characteristics and the optimum rear contact spacing is investigated. The highly nonideal I-V curves of rear point-contacted high-efficiency silicon solar cells made at the University of New South Wales (UNSW) are modeled with a high degree of accuracy. This is achieved by properly accounting for the complex recombination behavior at the rear oxidized surface. The 2D simulations show that the nonideal I-V curves result from the unequal capture cross sections of electrons and holes at the rear Si-SiO2 interface and the surface band bending induced by positive oxide charges and metal/silicon work function differences. For the UNSW cells, optimum one-sun efficiency is obtained on 2 Ω cm substrates and rear contact spacings of 0.2–0.3 mm. The 2D simulations presented in this work clearly confirm the experimental findings and reveal the physical mechanisms which favor this particular contact design.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355694
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  • 3
    Electronic Resource
    Electronic Resource
    Bonding between CO and the MgO(001) surface: A modified picture (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 2010-2018 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The interaction energy and equilibrium distance for adsorption of CO on a perfect MgO(001) surface has been calculated, using a cluster approach for representing the surface. The cluster size has been varied from one single Mg2+ ion up to Mg14O5. Ab initio model potentials (AIMP) were used to embed the explicitly described cluster while the rest of the crystal was taken to be point charges. The AIMP model potentials are shown to be a necessary and reliable improvement, compared with using only point charges as a model for the surrounding crystal. It is found that the electrostatic attraction and Pauli repulsion almost cancel each other and the small binding energy obtained is ascribed to dispersive forces. The interaction energy is calculated to be 0.07–0.09 eV (depending on which approach to basis set superposition errors corrections is taken); this is rather low in comparison with the experimental value of 0.3–0.4 eV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466553
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  • 4
    Electronic Resource
    Electronic Resource
    Low-temperature catalytic oxidation of 1,4-dichlorobenzene (1991)
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 30 (1991), S. 89-95 
    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/ie00049a013
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  • 5
    Electronic Resource
    Electronic Resource
    Double deprotonation of ruthenium(II) cations containing 1,2-dimethyl-substituted .eta.6-arenes. Protonation of the resulting exo-coordinated (o-xylylene)ruthenium(0) complexes and x-ray crystal structures of the agostic (.eta.3-pentamethylbenzyl)ruthenium(II) complexes [Ru{.eta.3-(HCH2)(CH2)C6Me4}{(Z)-Ph2PCH:CHPPh2}(PMe2Ph)]PF6 and [Ru{.eta.3-(HCH2)(CH2)C6Me4}(PMe2Ph)3]PF6 (1992)
    s.l. : American Chemical Society
    Organometallics 11 (1992), S. 3069-3085 
    Details
    ISSN: 1520-6041
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/om00045a022
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  • 6
    Electronic Resource
    Electronic Resource
    Avalanche breakdown in p-n AlGaAs/GaAs heterojunctions (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 6917-6923 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Avalanche breakdown in abrupt p-n AlGaAs/GaAs heterojunctions is invesigated, and the breakdown voltage, the maximum electric field, and the depletion layer width are calculated as functions of the doping densities, the temperature, and the AlAs mole fraction in AlGaAs. The model employed is an extension of Hauser's model of homojunction breakdown [Appl. Phys. Lett. 33, 351 (1978)], and it includes the effects of the band offsets at the interface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345085
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  • 7
    Electronic Resource
    Electronic Resource
    Diffusion effects in p-type PtSi Schottky diodes under reverse bias (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 3601-3604 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: At low temperature, the dominant current transport process of a p-type PtSi Schottky diode on a moderately doped Si substrate is thermionic emission over the barrier. In this paper, current has been measured as a function of temperature at a fixed reverse bias for several Schottky diodes. It is found that diffusion effects due to the limitation upon the diffusion rate through the space-charge region can become significant under some conditions. At moderate field, these conditions are calculated to be at a temperature of 150 K or greater, depending on the doping density of the devices. I-V-T measurements were carried out on several Schottky devices fabricated in slightly different ways, and the diffusion effect was observable in some of these devices. A numerical routine is utilized to fit the experimental data to a combined thermionic emission-diffusion theory in these regions. It is found that the experimental results fit this theory well. In addition, the acceptor density at which diffusion becomes the dominant current at 80 K under moderate field is calculated to be around 5×1011 cm−3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348505
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  • 8
    Electronic Resource
    Electronic Resource
    Characteristics of p-type PtSi Schottky diodes under reverse bias (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 4127-4132 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The characteristics of p-type PtSi Schottky diodes are determined under reverse bias at cryogenic temperatures. Zero-bias and flat-band barrier heights of 0.242 and 0.263 eV, respectively, are evaluated from the data. In addition, the observed lack of excess barrier lowering (other than the image force lowering) is discussed. This excess barrier lowering has previously been postulated to arise from the penetration of the tail end of the metal wave function into the midgap of the semiconductor. Reverse activation analysis is reported for 30 Schottky diodes and an average experimental effective Richardson constant of 45 A/cm2 K2 is determined. The difference from the theoretical value (32 A/cm2 K2) is attributed to the temperature coefficient of the barrier height. A value of 2.7×10−5 eV/K for this coefficient is obtained, which is at least one order of magnitude smaller than the variation of the bandgap of silicon. This provides further evidence that the barrier of the p-type PtSi Schottky diode is pinned at the valence-band edge, in agreement with previous results and the expectation inferred from the n-type measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346254
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  • 9
    Electronic Resource
    Electronic Resource
    Erratum: "Band edge optical absorption in intrinsic silicon: Assessment of the indirect transition and disorder models'' [J. Appl. Phys. 73, 3988 (1993)] (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6462-6462 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355344
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  • 10
    Electronic Resource
    Electronic Resource
    Band edge optical absorption in intrinsic silicon: Assessment of the indirect transition and disorder models (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 3988-3996 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two competing theories of the optical absorption edge of intrinsic crystalline silicon, the indirect transition theory, and the recent disorder (Urbach edge) theory, are assessed critically. The assessment of the indirect transition theory includes an attempt to predict, by the use of the luminescence spectrum and the principle of detailed balance, the optical absorption in the wavelength range where it is mediated by the simultaneous absorption of up to three phonons. The inability of this method to accurately reproduce the experimental data is used to illustrate limitations of the indirect transition theory: its neglect of band degeneracy and its failure to explain the different absorption replica shapes for different phonons. In its published form, the disorder theory does not explicitly address the question of the role of indirect processes or the nature of the strong transitions which trigger the disorder processes. Some of the evidence presented in favor of the theory is shown to be in doubt. The possible synthesis of the two theories is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352864
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