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  • 1
    Electronic Resource
    Electronic Resource
    Breit–Wigner description of resonant tunneling (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2453-2455 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Analytic properties of scattering amplitudes are used to develop Breit–Wigner parametrizations of resonant tunneling currents in heterostructures. The analysis reveals a problem in using conventional Breit–Wigner resonance expressions to describe the important regions of peak current and negative differential resistance which occur when resonances are near the emitter threshold. Commonly used Breit–Wigner expressions (a) do not incorporate the correct threshold branch points, (b) do not possess the correct limit at threshold, and (c) do not satisfy unitarity both above and below threshold. Expressions which avoid such difficulties are deduced and used to parametrize tunneling current formulas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102000
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  • 2
    Electronic Resource
    Electronic Resource
    Is intrinsic bistability really intrinsic tristability? (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 2115-2117 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The issue of intrinsic bistability in resonant tunneling devices is examined analytically and quantitatively. The results indicate that the putative argument for intrinsic bistability is actually an argument for intrinsic tristability. If a third stable configuration really exists, it might be hard to access experimentally although its existence could have consequences for high-speed device applications. If an intrinsic bistable regime is ipso facto a tristable regime, then an experimental search for a third stable configuration could provide persuasive evidence for the physical mechanism commonly advocated as the basis for intrinsic bistability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101145
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  • 3
    Electronic Resource
    Electronic Resource
    Spike train generation and current-to-frequency conversion in silicon diodes (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 478-480 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A device physics model is developed to analyze spontaneous neuron-like spike train generation in current driven silicon p+-n-n+ devices in cryogenic environments. The model is shown to explain the very high dynamic range (107) current-to-frequency conversion and experimental features of the spike train frequency as a function of input current. The devices are interesting components for implementation of parallel asynchronous processing adjacent to cryogenically cooled focal planes because of their extremely low current and power requirements, their electronic simplicity, and their pulse coding capability, and could be used to form the hardware basis for neural networks which employ biologically plausible means of information coding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101858
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  • 4
    Electronic Resource
    Electronic Resource
    Interfacial work functions and extrinsic silicon infrared photocathodes (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1738-1740 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is shown that n+ and/or p+ contacts on p-i-n diodes can function as solid-state photoemitters at temperatures (approximately-less-than)20 K. Infrared radiation can excite electrons or holes over small n-i or p-i interfacial barriers and into the intrinsic region when the diode is forward biased. Photoelectric thresholds in the far infrared corresponding to 37 and 61 μm cutoffs have been observed for silicon devices using a Fourier transform spectrometer. Suggestions are made to tailor the cutoff wavelengths using different concentrations of various impurities near the metal-insulator transition. Epitaxially grown multilayered (superlattice) detectors are proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102203
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  • 5
    Electronic Resource
    Electronic Resource
    Erratum: Exchange interactions in quantum well subbands [Appl. Phys. Lett. 53, 1931 (1988)] (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 206-206 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102380
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  • 6
    Electronic Resource
    Electronic Resource
    Exchange interactions in quantum well subbands (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1931-1933 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is shown that exchange interactions in the two-dimensional electron gas in quantum wells could cause observable effects on subband energies and intersubband transition energies. In the case of doped quantum wells, the intrasubband exchange interaction can produce an energy shift which is substantially larger than the direct Coulomb energy shift. Theoretical estimates of such shifts are compared with experimental measurements of the infrared photoconductivity of multiple quantum well AlGaAs/GaAs structures with wells doped at about 1018 cm−3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100327
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  • 7
    Electronic Resource
    Electronic Resource
    Interfacing multispectral sensors to real time processors based on neural network models (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 961-963 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experiments have been carried out to demonstrate and study the interfacing of silicon sensors to silicon devices which represent first stage elements of an artificial neural network. Sensor outputs (network inputs) are photocurrents associated with infrared, visible, or ultraviolet light. First stage linear coding of input current into the pulse rate of a stereotypical neuronlike spiketrain output has been achieved with a dynamic range of more than 106. For 1 pA inputs, the estimated noise referred to input is 10 fA. Network elements are shown to obey equations of the same form as equations which occur in nonlinear neural network models recently analyzed by Hopfield [Proc. Natl. Acad. Sci. 81, 3088 (1984)] and previously studied by Sejnowski [J. Math. Biology 4, 303 (1977)].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98776
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  • 8
    Electronic Resource
    Electronic Resource
    Derivation and correction of the Tsu–Esaki tunneling current formula (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 693-696 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The theoretical basis of the Tsu–Esaki tunneling current formula [Appl. Phys. Lett. 22, 562 (1973)] is examined in detail and corrections are found. The starting point is an independent particle picture with fully antisymmetrized N-electron wave functions. Unitarity is used to resolve an orthonormality issue raised in earlier work. A new set of mutually consistent equations is derived for bias voltage, tunneling current, and electron densities in the emitter and collector. Corrections include a previously noted kinematic factor and a modification of emitter and collector Fermi levels. The magnitude of the corrections is illustrated numerically for the case of a resonant tunneling current-voltage characteristic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343539
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  • 9
    Electronic Resource
    Electronic Resource
    New degrees of freedom in resonant tunneling heterostructure devices (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 4344-4348 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Lateral degrees of freedom in resonant tunneling heterostructure devices are investigated in a model which omits the usual assumption that the electric field and current density are laterally uniform. Relaxation of spatially nonuniform configurations of field and current into the usual uniform configurations is examined. For certain device parameters and operating conditions, stable nonuniform configurations are found in addition to the conventional uniform configurations. An eigenvalue criterion for stability is established. The possibility of nonuniform configurations with spatially localized oscillation is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348379
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  • 10
    Electronic Resource
    Electronic Resource
    Resonant tunneling time delay and quantum well sheet density (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 1227-1230 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Time delays, dwell times, resonant state lifetimes, and electron sheet densities associated with tunneling through quantum well structures are analyzed from a scattering theory (S-matrix) viewpoint. Some of the results differ from intuitively motivated expressions which have appeared in the resonant tunneling literature. It is shown that the sheet density is given by a formula similar to the Tsu–Esaki formula [Appl. Phys. Lett. 22, 562 (1973)] for current density. Sheet density and dwell time are related to Hermitian matrices which are expressed in terms of the S-matrix and in terms of partial widths associated with resonant states.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343468
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