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  • 1
    Electronic Resource
    Electronic Resource
    Resonant tunneling in (001)- and (111)-oriented III–V double-barrier heterostructures under transverse and longitudinal stresses (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 7763-7769 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Calculations of the effects of external stress on the current–voltage characteristics of double-barrier (001)- and (111)-oriented resonant tunneling devices are presented. Crystal strains arising from the application of external pressure and, in pseudomorphic structures, lattice mismatch cause shifts in the conduction and valence bands of the well and barrier layers with respect to the unstrained alignment. For certain stress orientations piezoelectric effects give rise to internal electric fields parallel to the current direction. The combined piezoelectric and band-structure effects modulate the transmission resonances which control the shape of the current versus voltage characteristics of the structures. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362381
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  • 2
    Electronic Resource
    Electronic Resource
    Piezoelectric effect in (001)- and (111)-oriented double-barrier resonant tunneling devices (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 7770-7774 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We show experimentally that current–voltage characteristics of double-barrier resonant tunneling devices (DBRTDs) can be modified by internal polarization fields due to the piezoelectric effect induced by external uniaxial stresses. Electric polarization fields, perpendicular to the interfaces, arise in DBRTDs grown on (001)-oriented substrates under uniaxial, compressive stresses parallel to the (110) or (11¯0) crystal orientations, and in DBRTDs grown on (111)B-oriented substrates under stress parallel to (111) crystal orientation. The voltages at which the resonant tunneling current peaks occur (peak voltages) are sensitive to the polarization fields induced by external stresses. The peak voltages can shift to more positive voltages or more negative voltages depending on the directions of applied stresses. We measured current–voltage characteristics of AlAs/GaAs/AlAs double-barrier resonant tunneling structures as a function of external stresses at 77 K. Uniaxial stress was applied parallel to the (110) and the (11¯0) crystal orientations for (001)-oriented DBRTDs, as well as to the (111) orientation for (111)B-oriented DBRTDs. With the substrates grounded in all the measurements, we found that the peak voltages shift to more positive voltages for (001)-oriented DBRTDs under stress along the (110) orientation and for (111)-oriented DBRTDs under the stress along (111) orientation, and to more negative voltages for (001)-oriented devices under stress along the (11¯0) orientation. The results are in agreement with our calculations published in the preceding article, which take into account the piezoelectric effect and band alignment under stress. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362382
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  • 3
    Electronic Resource
    Electronic Resource
    Linear in-plane uniaxial stress effects on the device characteristics of AlGaAs/GaAs modulation doped field effect transistors (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 502-505 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The current voltage relationships of AlGaAs/GaAs modulation doped field effect transistors (MODFETs) were measured as a function of applied uniaxial stress. Stresses in the [110] and [11¯0] directions on MODFETs that were grown on a (001) substrate produced threshold shifts of opposite sign. Stresses in [110] and [11¯0] directions resulted in threshold voltage pressure coefficients of −15 and 64 mV/Kbar, respectively. The asymmetric shifts in the threshold voltages are attributed to piezoelectric effects. In addition, stress induced changes in the slopes of the transconductance versus gate-to-source voltage relationships were also measured. For stresses in the [110] and [11¯0] directions, the dependencies were 0.4 and −0.7 mS/(VKbar), respectively.© 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364126
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  • 4
    Electronic Resource
    Electronic Resource
    Electronic structure of dual gate quantum wire (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 2517-2521 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electronic structure of a novel nanometer scale semiconductor quantum wire structure [S. Y. Chou and Y. Wang, Appl. Phys. Lett. 63, 788 (1993)] has been calculated self-consistently. The structure has two control parameters, the voltage applied to a split gate and the voltage applied to a wire gate. The influences of both the split gate and the narrow wire gate which is placed inside the gap of the split gate, on the electronic structure of the system are examined. We show that varying the voltage on either the split gate or the wire gate changes the induced quantum wire confinement potential profile, the energy level spacing, the channel electron density, and the effective channel width. Results for the ballistic conductance of the device as a function of the two control voltages are extracted from the electronic structure calculations and are found to be in satisfactory agreement with experimental data. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361116
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  • 5
    Electronic Resource
    Electronic Resource
    Electron–electron interaction in three-dimensional model quantum box (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 1798-1803 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of electron–electron interaction on the electronic structure of a three-dimensional model quantum box are studied. The potential in the lateral plane of the quantum box is taken to be a two-dimensional harmonic potential, and an infinite quantum-well potential is used to represent the confinement in the vertical direction. Three-dimensional two-electron wave functions are constructed by the configuration interaction technique. Exchange and correlation are found to affect the electronic structure strongly. The effect of the finite thickness of the quantum box on the electronic structure is examined. It is shown that the electron–electron interaction can induce interesting polarization effects not only in the lateral plane but also in the vertical direction of the quantum box. Numerical results based on GaAs material parameters are presented. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360211
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  • 6
    Electronic Resource
    Electronic Resource
    Spectrally agile far-infrared detector using an n-i-p-i superlattice (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 956-960 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We propose a spectrally agile far-infrared detector based on an InSb n-i-p-i superlattice. We show that the spectral response of the detector can be tuned with an applied electrical bias that modulates the tunneling-assisted interband absorption coefficient by changing the internal electric fields. Calculations for several possible superlattice designs are presented and the limitation on the design parameters imposed by the tunneling current is discussed. It is shown that the detector can distinguish between blackbodies with temperatures in the range of 200–400 K independent of the distance between the object and the detector. We also present a simple discussion of the response time that can be expected from such a detector and of the noise sources that will limit its performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343471
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  • 7
    Electronic Resource
    Electronic Resource
    Gate current of modulation-doped field-effect transistors (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 1541-1546 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a new room-temperature model for modulation-doped field-effect transistors and heterojunction insulated gate field-effect transistors that accounts for effects induced by the gate current at large gate voltages. For large gate currents the quasi-Fermi levels in the GaAs channel and the AlGaAs barrier layers are different because of the limited electron exchange imposed by the heterojunction band offset. As a consequence, the channel electron concentration for large gate voltages exceeds the value expected for the n-AlGaAs/GaAs material system in thermal equilibrium. The channel electron capacitance can have two peaks as a function of gate voltage leading to similar structure in the gate voltage dependence of the transconductance. We find good agreement between our calculated and measured gate currents as a function of the gate voltage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341830
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  • 8
    Electronic Resource
    Electronic Resource
    Channel formation in organic field-effect transistors (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 4312-4318 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Results of two-dimensional electrostatic modeling of organic field-effect transistors, focusing on the formation of the conductive channel, are reported. The effect on channel formation of the choice of the source and drain contact metal is investigated for both top- and bottom-contact device structures. High-work-function metal (e.g., gold) source and drain contacts produce a conducting p-type region near these contacts. In contrast, low-work-function metal source and drain contacts (e.g., magnesium) lead to depleted regions. In the center of the device, between the source and drain contacts, the channel carrier density at a fixed gate bias is determined by the work function of the gate contact material, and is essentially independent of the metal used to form the source and drain contacts. The principal difference between top- and bottom-contact structures is the spatial variation of the charge density in the vicinity of the source and drain contacts. The channel carrier density for a fixed gate bias (and gate contact material) between the source and drain electrodes is essentially the same for the two structures. Finally, the dependence of the transistor threshold voltage on the gate contact metal work function and the device implications of the spatial variation of the induced charge density are discussed. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1453509
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  • 9
    Electronic Resource
    Electronic Resource
    In-plane uniaxial stress effects of AlGaAs/GaAs modulation doped heterostructures characterized by the transmission line method (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 3741-3746 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Transmission line method patterns were fabricated on AlGaAs/GaAs heterostructures to measure the effect of uniaxial stress on the heterojunction two-dimensional electron gas resistivity and the contact resistance. Uniaxial compressive stress was applied in the [110] and [11¯0] directions of heterojunctions fabricated on (001)-oriented GaAs substrates. Fitting the measured data to a lumped resistor model yielded normalized sheet resistivity stress coefficients of −3.2%/kbar and 12.6%/kbar for stress in the [110] and [11¯0] directions, respectively. From these coefficients we obtain a value for the piezoelectric constant e14 of Al0.4Ga0.6As to be −0.26 C/m2, which when linearly extrapolated to AlAs gives −0.40 C/m2 compared to the value −0.225 C/m2 calculated by Hübner [Phys. Status Solidi B 57, 627 (1973)]. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368552
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  • 10
    Electronic Resource
    Electronic Resource
    Optical modulation of light transmission in GaAs doping superlattices (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 3293-3295 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report results of measurements of optically modulated optical transmittance of GaAs doping superlattices. The data extend over a spectral region of 1.39–1.58 eV. We find that the peak transmission modulation reaches 21% for a 2.6-μm-thick sample and an optical pump power density of 〈10 W/cm2 at room temperature. We interpret our data in the framework of a simple semiclassical model that includes the Franz–Keldysh effect both below and above the bulk GaAs band gap, as well as band filling and band shrinkage effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342665
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