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  • 1
    Electronic Resource
    Electronic Resource
    Semiconductor electron-wave slab waveguides (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 1483-1485 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A one-dimensional semiconductor quantum well can act as a waveguide for ballistic electrons owing to the quantum mechanical wave behavior of these electrons. The allowed modes in an asymmetric quantum well slab waveguide are quantified. Electron waveguiding can occur for energies above one or both of the potential barriers. Due to dispersion, each electron waveguide mode has an upper-energy cutoff as well as a lower-energy cutoff. An example waveguide consisting of Ga0.85Al0.15As (substrate), GaAs (film), and Ga0.70Al0.30As (cover) is treated. This structure is a single-mode electron waveguide for [100] GaAs thicknesses of from 6 through 31 monolayers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344404
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  • 2
    Electronic Resource
    Electronic Resource
    Semiconductor superlattice interference filter design (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 2535-2540 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The quantitative analogies that have been previously established [J. Appl. Phys. 65, 814 (1989)] between electron wave propagation in semiconductors and optical wave propagation in dielectrics may be used to translate thin-film optical device designs into semiconductor superlattice device designs. The procedure for this direct mapping is also described in the above reference. The resulting designs, however, have compositions that are not constrained to be within a usable compositional range and they have layer thicknesses that are not constrained to be integer multiples of a monolayer thickness. In the present work, a systematic design procedure is presented that includes these required practical constraints. This procedure is then applied to the design of Ga1−xAlxAs superlattice narrow interference filters. For pass kinetic energies in the range of 0.14–0.20 eV, compositions (values of x) and numbers of monolayer thicknesses needed to produce quarter-wavelength layers are calculated. The detailed design of an example narrow bandpass (15.4 meV) filter with a pass electron energy of 0.20 eV is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342775
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  • 3
    Electronic Resource
    Electronic Resource
    Electron wave optics in semiconductors (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 814-820 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Starting from fundamental principles, quantitative analogies between quantum mechanical electron waves in semiconductor materials and electromagnetic optical waves in dielectrics are presented. This, in turn, suggests many new classes of electron wave optical devices such as narrow-band superlattice interference filters. Phase effects associated with an electron wave are incorporated using an "electron wave phase refractive index'' that is proportional to the square root of the product of the electron effective mass and the electron kinetic energy. It is shown that the amplitude of an electron wave is analogous to the electric field of a TE polarized electromagnetic wave (or to the magnetic field of a TM polarized electromagnetic wave) in a dielectric. Amplitude effects associated with an electron wave are incorporated using an "electron wave amplitude refractive index'' that is proportional to the square root of the ratio of the kinetic energy to the effective mass. A simple expression for the critical angle for total internal reflection of an electron wave is developed. By analogy to the electromagnetic optical case, the total electron transmissivity and reflectivity of a semiconductor superlattice is presented. For illustration, an electron wave interference filter that is the counterpart of a multilayer quarter-wave stack thin-film optical interference filter is designed as a variable band gap and variable thickness semiconductor superlattice. Numerous new electron optical devices are suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343071
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  • 4
    Electronic Resource
    Electronic Resource
    Theory of the velocity-field relation in AlGaAs (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 5004-5008 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present ensemble Monte Carlo calculations of the steady-state electron drift velocity as a function of applied electric field in Al0.32 Ga0.68 As. The effect of various material parameters on the calculated velocity is assessed by varying each parameter independently by ±20%. It is found that both the optical phonon energy and intervalley separation energy alter the peak electron velocity greatly. Variations in the dielectric constants and central valley effective mass have little effect upon the peak drift velocity, but act to alter the threshold electric field. It is further found that the threshold electric field is greater in Al0.32Ga0.68As than in GaAs even though the central-to-satellite valley separation energy is less in AlGaAs. The combined effects of a greater central valley effective mass and a larger phonon energy in AlGaAs result in a greater threshold field. Finally, we present sets of material parameters useful in Monte Carlo models for both GaAs and AlGaAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.340446
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  • 5
    Electronic Resource
    Electronic Resource
    Theory of resonant tunneling in a variably spaced multiquantum well structure: An Airy function approach (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 614-623 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A theoretical study of resonant tunneling in multilayered heterostructures is presented based on an exact solution of the Schrödinger equation under the application of a constant electric field. By use of the transfer matrix approach, the transmissivity of the structure is determined as a function of the incident electron energy. The approach presented herein is easily extended to many layer structures where it is more accurate than other existing transfer matrix or Wentzel–Kramers–Brillouin (WKB) models. The transmission resonances are compared to the bound-state energies calculated for a finite square well under bias using either an asymmetric square-well model or the exact solution of an infinite square well under the application of an electric field. The results show good agreement with other existing models as well as with the bound-state energies. The calculations were then applied to a new superlattice structure, the variably spaced superlattice energy filter, which is designed such that under bias the spatial quantization levels fully align. Based on these calculations, a new class of resonant tunneling superlattice devices can be designed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338213
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  • 6
    Electronic Resource
    Electronic Resource
    The variably spaced superlattice electroluminescent display: A new high efficiency electroluminescence scheme (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 5410-5418 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a new, highly efficient dc electroluminescent display. A variably spaced superlattice scheme is suggested herein which can produce high-energy injection of electrons into a ZnSe:Mn active layer in which impact excitation of the Mn centers can occur. The device is predicted to operate at an applied external bias an order of magnitude less than the best dc electroluminescent device to date. The device is predicted to have comparable brightness, since it operates in the saturation regime. The improved efficiency stems from avoiding significant energy loss to phonons. The electrons sequentially tunnel through a multilayer stack under bias and emerge into the active layer at an energy equal to the conduction-band bending. The injection energy is chosen to coincide with the impact excitation energy of the Mn centers. Different device designs are presented and their performance is predicted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338281
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  • 7
    Electronic Resource
    Electronic Resource
    Semiconductor quantum wells as electron wave slab waveguides (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 1842-1848 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A quantum well in a semiconductor can act as a slab waveguide for electron waves in a manner analogous to the way a layered dielectric can act as a slab waveguide for electromagnetic waves (e.g., as commonly employed in integrated optics). In this work, the case of a general electron asymmetric slab waveguide (a quantum well comprised of three materials each with a different potential energy and a different effective mass) is analyzed and the conditions for electron waveguiding are quantified. Electron waveguide modes exist for electron energies in the well and for electron energies above one or both of the potential energy barriers. Furthermore, due to dispersion, each electron waveguide mode has an upper-energy cutoff as well as a lower-energy cutoff. This is in contrast to electromagnetic guided modes which typically have only lower-energy (low-frequency) cutoffs. At the upper-energy cutoff the electron wave is refracted into the substrate and/or cover. An example quantum well waveguide consisting of Ga0.80 Al0.20 As (substrate), GaAs (film), Ga0.55 Al0.45 As (cover) is analyzed. This structure is a single-mode electron waveguide for GaAs thicknesses of from 5 (1.413 nm) to 26 monolayers (7.349 nm).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344357
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  • 8
    Electronic Resource
    Electronic Resource
    Semiconductor biased superlattice tunable electron interference filter/emitter (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 1494-1497 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is shown that a voltage-biased semiconductor superlattice structure can serve simultaneously as a tunable electron-wave interference filter and electron emitter. A systematic design procedure for selecting the quantum well and barrier widths to be alternately high and low electron refractive indices and a quarter (or a half) of an electron wavelength in thickness is developed. A practical narrow-band filter/emitter consisting of layers of Ga1−xAlxAs and designed to emit 0.20-eV electrons is presented and analyzed. Such a structure would serve well as a tunable hot-electron emitter in ballistic transistors, and in future guided electron-wave integrated circuits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344408
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  • 9
    Electronic Resource
    Electronic Resource
    Self-consistent analysis of resonant tunneling in a two-barrier–one-well microstructure (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 2392-2400 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A self-consistent solution to the resonant tunneling problem is presented based on the simultaneous solution of the time-independent Schrödinger equation with the Poisson equation. The solution is obtained from a piecewise linear matching of Airy functions. The model is used to explore the effects of the self-consistent electron charge on the transmissivity and current-voltage characteristics of a double-barrier single-well GaAs-AlGaAs device. It is found that the self-consistent potential always acts to shift the negative differential resistance onset voltage to large positive values. The self-consistent field effectively acts to screen the positive applied voltage. Therefore, the effects of the self-consistent field can essentially be modeled by a smaller applied positive bias. It is further found that the effects of the self-consistent field are most prevalent at high temperatures, ∼300 K, and at high dopings, 〉1.0×1018. It is necessary to include the self-consistent effects then when designing resonant tunneling structures within these constraints.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339472
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  • 10
    Electronic Resource
    Electronic Resource
    Theory and design of semiconductor electron-wave interference filter/emitters (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 6158-6167 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A voltage-biased semiconductor superlattice structure is designed to operate simultaneously as a continuously voltage-tunable, electron interference filter and as an electron emitter. Using the analogies between electromagnetic waves and electron de Broglie waves, a systematic procedure for designing the quantum wells and barriers comprising the electron-wave filter/emitter superlattice is developed. A generalized procedure for analyzing the electron-current transmittance and reflectance spectral responses of these superlattice structures is then presented. A practical, continuously tunable filter/emitter consisting of multiple layers of Ga1−xAlxAs (compositional superlattice) is designed to emit nearly monoenergetic 0.20-eV electrons by appropriate selection of the layer compositions and thicknesses. The constraints required to have thicknesses that are integer multiples of the monolayer thickness and to avoid phonon scattering of electrons into the L band are included. The filter/emitter is shown to have a wide tunable energy range. A sensitivity analysis of the device characteristics in the presence of fabrication errors reveals a very stable device response. Such quantum electron-wave devices could serve as continuously tunable hot-electron emitters in ballistic transistors and in future guided electron-wave integrated circuits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343599
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