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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2550-2556 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a comparison of two different methods of including the electron-electron long-range interaction on the dynamics of hot electrons in degenerate GaAs under transient conditions in two different hot electron transistor structures of 60- and 120-nm base widths, respectively. The first approach is quantum mechanically based while the second follows a semiclassical prescription. The calculated energy spectrum, velocity distribution, and percentage of injected carriers collected in the hot electron transistors are determined under three different conditions: the inclusion of the plasmon interaction through the quantum-mechanical formulation, the inclusion of the plasmon interaction through the semiclassical technique, and with no plasmon interaction. The calculated energy spectrums within the two plasmon models are qualitatively similar. They differ only by the extent to which the peaks are broadened and the absolute ratio of collected to injected carriers. Because of the very different energy relaxation within the plasmon models, the ratio of collected to injected electrons is predicted to be far smaller using the quantum-mechanical model than the semiclassical model. Subsequently, knowledge of the absolute ratio of the collected to injected carriers in a hot electron transistor would give some indication of the appropriateness of each model.
    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 72 (1992), S. 5277-5282 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ensemble Monte Carlo calculations of the steady-state electron drift velocity in degenerate bulk GaAs using a self-consistent algorithm specially tailored to directly include the electron-plasmon interaction are presented. The critical issues implicit in the direct approach are the mesh size, charge assignment to the mesh nodes, interpolation of the field at the particle location, and the frequency with which the solution of the Poisson equation is updated. All of these factors determine the stability of the system, the accuracy, and the computational time required in the calculation. Comparison is made to quantum mechanically based techniques in which the electron-plasmon interaction is treated as an additional scattering mechanism. It is found that the steady-state electron drift velocity in bulk degenerate GaAs calculated using the semi-classical approach for the electron-plasmon interaction is significantly less than that calculated assuming no electron-plasmon interaction is present. The steady-state drift velocity calculated using the quantum mechanical approach, wherein the electron-plasmon interaction is treated as a separate scattering mechanism, is affected in the opposite way, i.e., the velocity is greater than in the absence of the electron-plasmon interaction. Neither model can at present be considered complete and caution should be exercised in adopting either approach in device simulation until a more satisfactory model has been developed.
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  • 3
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The transmission and current-voltage characteristics of Ga1−xAlxAs superlattice electron-wave quantum-interference filter/emitter negative differential resistance devices are analyzed with and without the self-consistency requirement. The analysis neglects the scattering effects within the superlattice since it is assumed that it is very thin (less than the electron coherence length). Thus, the calculated characteristics correspond to the ballistic component of the current. For the non-self-consistent calculation the single-band effective-mass time-independent Schroedinger equation is solved. For the self-consistent calculation, the Schroedinger and Poisson equations are solved iteratively until a self-consistent electron potential energy and electron density are obtained. It is shown that suitably designed electron-wave quantum-interference filter/emitters can exhibit strong negative differential resistance in the current-voltage characteristics, similar to those of resonant tunneling diodes. For low-to-moderate (2–30 meV) Fermi energies in the conduction band of Ga1−xAlxAs (Si doping concentration less or equal to 2 × 1018 cm−3) and temperatures near 30 K (in the ballistic transport regime), it is shown that space-charge effects are relatively small and result in a slight shift of the current-voltage and transmission characteristics toward higher bias voltages. In a fashion similar to that occurring in resonant tunneling diodes, the self-consistent field in electron-wave filter/emitter negative differential resistance devices partially screens the positive applied bias. Designs of Ga1−xAlxAs resonant devices with current peak-to-valley ratios of ∼50 as well as nonresonant (not exhibiting negative differential resistance) devices are analyzed. The corresponding electron charge density distributions are also presented. Superlattice electron-wave filter/emitter negative differential resistance devices can be used as high-speed switches, oscillators, and as monoenergetic emitters in electroluminescent devices and photodetectors.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6854-6859 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A theoretical investigation is presented of the effect of ionized impurity scattering, electron-electron interaction, and degeneracy, both separately and collectively, on the bulk steady-state transport properties of degenerate GaAs. The calculations are performed using an ensemble Monte Carlo simulation that includes an analytic nonparabolic formulation of the three principal valleys in the conduction band and all of the important phonon scattering mechanisms. It is found that the overall velocity-field characteristic is determined primarily by the action of electron-plasmon scattering at high electric fields (near the intervalley threshold field). At lower fields, below which the electrons are not heated to the threshold energy for plasmon emission, ionized impurity scattering is the most dominant mechanism. In addition the effects of degeneracy are also important throughout. Only the short-range electron-electron interaction has little effect on the velocity-field curve owing to the fact that it does not alter the net momentum or energy of the electron gas in steady-state bulk material.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 3097-3103 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We compared two different formulations, the electron-field and electron-electron models, for electron-plasmon scattering in bulk semiconducting materials. The calculations employ three different expressions for the plasmon dispersion relation and are made at two different temperatures. It is found that the functional form of the dispersion relation greatly affects the electron-plasmon-scattering rate. The electron-field model is found to predict a higher scattering rate than the electron-electron model, independent of the form of the dispersion relation. Either model predicts the same order-of-magnitude scattering rate, which is found, in the case of bulk degenerate GaAs, to be comparable to the polar optical-phonon-scattering rate. Based on these calculations, plasmon scattering appears to be an important mechanism limiting electron transport in degenerate semiconductors and related semiconductor devices.
    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 69 (1991), S. 7844-7847 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present calculations based on an ensemble Monte Carlo simulation of the electron impact ionization rate in bulk InAs and Hg0.70Cd0.30Te at 77 K. The Monte Carlo calculation includes an analytic nonparabolic model of the conduction band, all of the dominant scattering mechanisms, and a nonparametrized model of the impact ionization rate. Calculations are first made of the ionization rate in bulk InAs and are compared to both experiment and previous Monte Carlo investigations. Updated material parameters are used as well as calculated values of the threshold energy and the ionization probability in the InAs simulation. Good agreement with previous Monte Carlo studies is achieved. Using a similar model, the electron ionization rate in bulk Hg0.70Cd0.30Te is studied. To our knowledge, this is the first study either theoretically or experimentally of electron impact ionization in long wavelength (5 μm) band-gap HgCdTe.
    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 71 (1992), S. 2736-2740 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present calculations of the k dependence of the impact ionization transition rate along the principal directions within the first Brillouin zone of bulk GaAs, Ge, and InAs. The calculations are performed using realistic energy-band structures determined using the k⋅p method. The impact ionization transition rate is determined from a two-body screened Coulomb interaction assuming energy and momentum conservation. The transition rate within the first two conduction bands of GaAs and Ge is calculated along with the rate within the first conduction band in InAs. It is found that the impact ionization transition rate depends strongly on the initiating electron k vector; the rate is greatest in all three materials at small values of k, i.e., within the gamma valley. This result implies that the k dependence of the ionization transition rate is important. The results also indicate that the rate is greatest for incident electrons at small k vector independent of whether the material is direct or indirect or of wide or narrow energy band gap. Nevertheless, the total impact ionization rate may prove to be relatively k independent since the total rate depends additionally on the nature of the nonequilibrium distribution function.
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 1055-1057 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present calculations based on an ensemble Monte Carlo program of the steady-state electron and hole drift velocities in bulk Ga0.52In0.48P and Al0.26Ga0.26In0.48P as well as present a list of material parameters for these substances which are of use in the modeling of semiconductor devices made from these material types. The calculations are made including a realistic treatment of both the conduction and valence energy bands based on the k*p method. All of the principal phonon scattering agents are included in our simulation as well.
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 6506-6509 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We compare the effect of two different formulations of the electron-plasmon scattering rate, the electron-field and electron-electron models, as well as different formulations of the dispersion relationship on the calculated bulk transport properties of degenerate GaAs. The calculations are performed using an ensemble Monte Carlo simulation which includes an analytical nonparabolic model of the principle valleys in the conduction band, and all of the dominant scattering mechanisms. It was previously found that the functional form of the dispersion relationship significantly alters the magnitude of the electron-plasmon scattering rate. As a consequence, the steady-state velocity-field characteristics are also significantly altered by as much as ∼40% by the choice of the dispersion relation. It is further found that the choice of either the electron-electron or electron-field model does not by itself significantly alter the calculated results. Therefore, either model can be used to describe the effects of electron-plasmon scattering in degenerate bulk materials.
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 3864-3871 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this article, we present a comprehensive, full band theoretical study of the high field, hole transport properties of the 4H phase of silicon carbide (4H-SiC). The calculations are performed using a full band ensemble Monte Carlo simulation that includes numerically tabulated impact ionization rates, and phonon and ionized impurity scattering rates. In addition, the simulation includes a mechanism, interband tunneling, by which the holes can move between bands in the proximity of band intersection points. It is found that there exists a significant anisotropy in the calculated steady-state hole drift velocity for fields applied parallel and perpendicular to the c-axis direction. Good agreement with experimental measurements of the hole initiated impact ionization coefficient for fields applied along the c axis is obtained, provided that interband tunneling in the proximity of band intersections is included in the model. If interband tunneling is not included, the calculated ionization coefficients are orders of magnitude lower than the experimental measurements. © 2000 American Institute of Physics.
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