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  • 1
    Electronic Resource
    Electronic Resource
    S-type switching characteristics from transverse transport in multiquantum well diodes (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 4417-4421 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: S-type switching characteristics have been observed at room temperature in AlAs/GaAs multiquantum well diodes at low forward bias. The multiquantum well structure consisted of a set of 10 periods of undoped 50-nm AlAs barriers with 50-nm n+ (1×1018/cm3) GaAs quantum wells inserted between a p+-GaAs anode and n+-GaAs cathode. A threshold voltage for switching from the low to high conductance state of 2.2 V was measured and a minimum holding voltage in the high conductance state of 0.9 V was observed. Switching to the high conductance state occurs due to impact ionization of electrons out of the heavily doped n+ wells forming positive space charge which enhances the cathode field and thereby electron injection giving rise to a positive feedback mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352208
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  • 2
    Electronic Resource
    Electronic Resource
    A thermionic-field-diffusion model for Npn bipolar heterojunction phototransistors (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 1427-1437 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This article describes the development of a thermionic-field-diffusion model for use in the analysis and design of abrupt, single heterojunction bipolar phototransistors (HPTs) for use in HBT-based optical receivers. In particular, included in this approach are the effects of a dc base bias on the optical gain and device performance. Taking into account the optical generation, the excess electron concentration at the emitter end of the quasi-neutral base is initially determined using a matching of the thermionic field emission across the emitter-base heterojunction with the diffusion current at the emitter end of the base. At the collector end of the base region, a finite electron concentration is used based on the collector current density. The results are used to determine the electron profile in the quasi-neutral base region and the diffusion components to the emitter and collector currents. To determine the device's optical gain, the photocurrent and the small signal current gain are calculated. The dominant component in the photocurrent is found to be due to optical absorption in the base-collector space charge region. For backside illumination, the collector component becomes larger. The base width and electron diffusion length control the current gain and thereby the optical gain. The model is used to quantify the effects of the device's structure on the optical gain. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365920
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  • 3
    Electronic Resource
    Electronic Resource
    Hole transport and quasi-Fermi level splitting at the emitter-base junction in Pnp heterojunction bipolar transistors (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 1949-1955 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hole transport across the emitter-base heterojunction in Pnp heterojunction bipolar transistors is considered and the amount of hole quasi-Fermi level splitting at the interface is analyzed. Hole injection at the emitter is shown to significantly limit the emitter current to a level more than an order of magnitude less than that predicted by the hole-base diffusion model. Due to the low hole mobility, hole drift diffusion across the emitter-base space charge region is shown to be of comparable importance to thermionic-tunneling emission in controlling hole injection into the base. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369186
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  • 4
    Electronic Resource
    Electronic Resource
    Early stage electromigration in gold thin films (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 4248-4254 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The early stage of electromigration in thin gold films on polyimide has been investigated at room temperature using the resistometric technique. While the resistance increase is initially linear, a saturation tendency is observed for longer stressing times at all stress current densities. A simple model is described which relates the saturation behavior in the resistance change to the buildup of mechanical stress gradients, which produce a counterflux of metal ions proportional to the stress gradient. The stress gradients arise due to nonuniformity in the grain size in the polycrystalline thin metal films which produces cluster regions of small grain size alternating with regions of large or near-bamboo grain size, which have larger and smaller metal ion diffusivities, respectively. The dependence of the maximum level of the resistance's change and the rate of resistance increase on the stress current density are experimentally characterized and compared with the model's predictions with good agreement. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368641
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  • 5
    Electronic Resource
    Electronic Resource
    Refinements in the method of moments for analysis of multiexponential capacitance transients in deep-level transient spectroscopy (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 182-190 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The analysis of multiexponential capacitance transients that arise in deep-level transient spectroscopy has been examined. The method of moments, a technique that provides a reliable method for resolution of a multiexponential capacitance transient into its exponential components, has been adapted and enhanced by incorporating an initial fast Fourier transform to extract the base-line offset, and a refinement in the cutoff correction to the moments integrals which improves convergence and accuracy. In addition, the mean displaced ratio smoothing algorithm has been incorporated and shown to improve the method's accuracy in the presence of noise. For the case where the response is not significantly convoluted with the excitation, a simplified form of the method of moments technique provides a simple and more direct determination of the exponential components. Examples of results for simulated data are provided illustrating application of the analysis. The limitations of the technique in determining the number of exponential components, their amplitudes and emission rates, and the applicability of the smoothing algorithm are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338852
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  • 6
    Electronic Resource
    Electronic Resource
    Gummel–Poon model for Npn heterojunction bipolar phototransistors (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 3581-3592 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A Gummel–Poon model for abrupt, single heterojunction Npn bipolar phototransistors is described including the effects of the dc base bias on the current and optical gains. Initially, the excess electron concentration at the emitter end of the quasineutral base is determined by matching the thermionic field emission across the emitter–base heterojunction with the diffusion current at the emitter end of the base and including the effects of optical generation. The result is used in determining the electron profile in the base from which the base charge and the electron component to the emitter and collector currents are calculated following the Gummel–Poon model. The photocurrent's components due to optical absorption in the quasineutral base, the base–collector space charge region, and the collector region are determined taking into account the nonuniform optical generation assuming topside illumination. A comprehensive description of the recombination current components is incorporated including the effects of optical absorption on recombination. The model is then used to calculate the dc and small signal current gain and the device's optical gain, and to examine the effects of dc biasing and the optical power level. The simulation results are compared with the available experimental results and reasonable agreement is found. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365677
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  • 7
    Electronic Resource
    Electronic Resource
    A thermionic-emission-diffusion model for graded base Pnp heterojunction bipolar transistors (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 8036-8045 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An analytical model which matches thermionic-emission-diffusion of holes across the emitter-base heterojunction with drift-diffusion transport across a graded base has been developed and used to examine the performance capabilities of InP-based Pnp heterojunction bipolar transistors (HBTs). Hole drift-diffusion across the emitter-base space charge region is shown to be of comparable importance to thermionic emission in controlling hole injection into the base. The effects of compositional base grading on the recombination currents is also taken into account. Compositional grading of the base is shown to enhance the device's current gain by as much as a factor of 10 by reducing recombination in the quasi-neutral base. More importantly, compositional base grading significantly reduces the base transit time which improves the device's peak cutoff frequency by as much as a factor of 1.5. A cutoff frequency as high as 35 GHz is found to be possible. The analysis indicates that composition grading of the base can be useful in developing high performance Pnp InP-based HBTs. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367896
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  • 8
    Electronic Resource
    Electronic Resource
    Eine Deuterium-Kernresonanzuntersuchung von Tantaldeuteriden (1977)
    Springer
    Colloid & polymer science 255 (1977), S. 925-925 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01617103
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  • 9
    Electronic Resource
    Electronic Resource
    Deuterium-und Niob-93-Kernresonanzuntersuchung von Niobdeuteriden (1978)
    Springer
    Colloid & polymer science 256 (1978), S. 284-284 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01550570
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