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  • 1990-1994  (8)
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Material
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Wide electron gas with periodic density modulation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 1460-1463 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the growth and characterization of a high-quality wide (∼2000 A(ring)) three-dimensional electron gas (3DEG) with periodic density modulation (period ∼200 A(ring)) in a modulation-doped wide parabolic potential well with a superimposed superlattice. Computer-controlled molecular beam epitaxy is used to synthesize the potential well as a graded AlxGa1−xAs digital alloy. The density-modulated 3DEG is compared to a uniform 3DEG of the same average density and width in a parabolic well without the superlattice. The Al mole fraction profiles for the two samples are measured in calibration runs immediately prior to actual growths. The density-modulated 3DEG has a low-temperature in-plane mobility in excess of 105 cm2/V s, compared to ∼2×105 cm2/V s for the uniform 3DEG. Capacitance-voltage measurements directly reveal the modulation of the density of the electron gas in the parabolic well with superimposed superlattice, and the absence of any density modulation for the gas in the bare parabolic well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351708
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Cryogenic field-effect transistor with single electronic charge sensitivity (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 631-633 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have fabricated matched pairs of cryogenic field-effect transistors with input charge sensitivity qn=0.01 e/(square root of)Hz at T=1.3 K, low input capacitance 0.4 pF, and extremely high input resistance in excess of 1015 Ω. Low leakage permits dc charge-coupled operation for times up to ∼103 s. The channel noise is characterized by a flat spectrum at high frequencies, and 1/f noise below a corner frequency fc〈1 kHz. These devices can resolve charge differences as small as qn(square root of)fc=0.4e.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111072
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Logarithmically graded quantum well far-infrared modulator (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 348-350 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have designed and fabricated a remotely doped "logarithmic'' potential well intended to have a tunable, narrow band absorption at far-infrared frequencies. A surface gate, epitaxially grown backgate, and contact to the electron gas in the quantum well allow independent control of the absorption frequency and the integrated absorption strength. The resonance frequency is dominated by the well curvature at the potential minimum and can be Stark shifted from ω/2πc=35 cm−1 to a frequency of 125 cm−1 by moving the electron gas through the asymmetric well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111144
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Infrared absorption of holes in a parabolic quantum well (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 2226-2228 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We observe the infrared absorption of holes in a wide graded AlxGa1−xAs parabolic quantum well to be at a single frequency, independent of the number of holes in the well. The resonant absorption frequency appears to be determined by the light hole mass, not the heavy hole mass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112771
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Conductance fluctuations and quantum chaotic scattering in semiconductor microstructures (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Chaos 3 (1993), S. 643-653 
    Details
    ISSN: 1089-7682
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We review recent experiments on aperiodic conductance fluctuations in ballistic GaAs/AlGaAs microstructures in the shape of a stadium billiard and a circle with point-contact leads, measured at millikelvin temperatures. Much of the observed behavior can be analyzed within a semiclassical approach to quantum chaotic scattering. After a brief review of the Landauer–Büttiker formulation of coherent transport, a variety of novel experimental phenomena and comparisons to semiclassical theory are presented. In particular, we discuss quantum-enhanced backscattering, the power spectrum of conductance fluctuations, crossover to the high-magnetic-field and tunneling regimes, and an application allowing the rate of phase-randomizing scattering to be measured in chaotic ballistic microstructures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.165927
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Remotely-doped superlattices in wide parabolic GaAs/AlxGa1−xAs quantum wells (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 1573-1575 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using the digital alloy technique, a series of high-mobility remotely doped GaAs/AlGaAs coupled multiple quantum well structures have been produced by the superposition of a wide parabolic quantum well and a square superlattice potential. Structures containing up to twenty superlattice periods with low temperature Hall mobilities from 23 000 to 100 000 cm2/V s have been produced. Fourier analysis of low field Shubnikov–de Haas oscillations, capacitance-voltage and Hall measurements of a 200 A(ring) period superlattice in a 1600 A(ring) wide parabolic well indicate the occupation of four superlattice periods with subband spacings in good agreement with theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107500
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Quantum Hall effect in InAs/AlSb quantum wells (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 1428-1430 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We demonstrate via low-temperature electron transport measurements the realization of a high-mobility ((approximately-greater-than)300 000 cm2/V s) two-dimensional electron gas in unintentionally doped InAs/AlSb single 120 A(ring) quantum wells grown on GaAs substrates by molecular beam epitaxy. Magnetoresistance and Hall measurements at T∼0.4 K show a well-formed quantum Hall effect, with effects due to spin splitting observed at filling factors as high as ν=17. The electron densities of these wells could be reduced by a factor ∼5 by using the negative persistent photoconductivity of these samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105188
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Low-density high-mobility electron gas in wide parabolic GaAs/AlxGa1−xAs wells (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2823-2825 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Remotely doped wide parabolic GaAs/AlxGa1−xAs wells are used to create thick ((approximately-greater-than) 1000 A(ring)) layers of high-mobility ((approximately-greater-than) 2×105 cm2/V s) electron gas with three-dimensional densities below (by a factor ∼3) the metal-insulator transition for doped GaAs. The temperature dependences of the Hall mobility and sheet density show no qualitative changes in a series of three samples spanning the metal-insulator transition. Shubnikov–de Haas oscillation measurements are used to determine the width of the electron gas layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103753
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    Paper (German National Licenses)
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