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  • 1
    Electronic Resource
    Electronic Resource
    Superlattice conduction in superlattice modulation-doped field-effect transistors (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 1503-1509 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We fabricated superlattice modulation-doped field-effect transistors where the doping is concentrated in GaAs narrow quantum wells separated by undoped AlGaAs barriers. As the doped AlGaAs regions are eliminated from such a structure, the concentration of traps generally associated with doping of AlGaAs is low. We observed the threshold voltage shift of only 140 mV with temperature change from 77 to 300 K (which should be compared to the shift of 200–300 mV in conventional modulation-doped field-effect transistors). Peak transconductances of 310 mS/mm at 300 K and 321 mS/mm at 77 K have been obtained. An interesting feature of this device is the complicated dependence of the transconductance on the gate voltage which has two peaks at 77 K and one sharp peak at 300 K. These peaks are caused by the parallel conduction paths in the superlattice at high gate voltages and by the gate leakage current. This parallel conduction in GaAs-doped quantum wells may be used in order to achieve larger voltage swings in superlattice modulation-doped field-effect transistors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338083
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Electronic subbands for AlxGa1−xAs/GaAs multilayer and superlattice structures (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 294-298 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have carried out calculations of the conduction bandstructure for GaAs/AlxGa1−xAs (0〈x≤1) multilayer structures with very thin layers. We report results for the case of a small number of layers for which the quasi-continuous bandstructure of a large superlattice is a poor approximation. Using a multivalley effective mass approach which includes nonparabolicity, we find that for large aluminum concentrations and thin layers the lowest bound state is derived from the X valley and is localized mainly in the alloy layers. The structures investigated have a range of design parameters which is useful for superlattice modulation-doped field-effect transistors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338819
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Mobility enhancement in highly doped GaAs quantum wells (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 1643-1645 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We propose the mechanism of the mobility enhancement in highly doped semiconductor quantum wells, based on the large increase in the carrier concentration using the field effect and on the corresponding reduction of the ratio of the ionized impurity concentration to the electron concentration. We observe the mobility enhancement in GaAs quantum wells doped at ∼2×1018 cm−3 at 77 K from 572 cm2/V s under the equilibrium conditions to approximately 2500 cm2/V s when a large carrier concentration is induced into the quantum well in a field-effect transistor. This effect can be used to increase the voltage and current swing in modulation-doped structures and may also allow us to achieve the mobility enhancement in new semiconductor materials with inherently large defect densities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338051
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Nonalloyed InGaAs/GaAs ohmic contacts for self-aligned ion implanted GaAs heterostructure field effect transistors (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 2455-2457 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nonalloyed indium gallium arsenide (InGaAs) ohmic contacts were investigated and successfully applied to both n- and p-type self-aligned ion implanted heterostructure field effect transistors (HFETs). The key factor was to preserve the doping concentration and structure integrity of the InGaAs layer during implant activation. Specific contact resistances in the range of 5×10−6–2×10−5 Ω cm for n and p HFETs were realized with this structure and process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108150
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    Paper (German National Licenses)
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