Simultaneous Measurements Of Electron And Hole Sweep-Out From Quantum-Wells And Modeling Of Photoinduced Field Screening Dynamics

    Authors

    J. A. Cavailles; D. A. B. Miller; J. E. Cunningham; P. L. K. Wa;A. Miller

    Comments

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    Keywords

    Optic Effect Device; Absorption; Electroabsorption; Dependence; Saturation; Engineering, Electrical & Electronic; Optics; Physics, Applied

    Abstract

    We measure both electron and hole escape times from a GaAs-AlGaAs quantum well in an electric field at room temperature. This gives important information for the design of high speed quantum-well modulator and optical switching devices. The measurements are made by picosecond optical pump-probe techniques on samples containing a single quantum well in a waveguide. The use of a single well avoids multiple well transport and resonant tunneling effects. Carriers excited in the quantum well by the pump beam result in a transient bleaching signal from excitonic saturation and, as they leave the well, a transient electroabsorption signal because the movement of charge partially screens the electric field. We model both processes, including important electrical equilibration processes (such as diffusive conduction) of the sample as a whole. This modeling and the use of two samples with asymmetric barrier heights allows the measurement of the electron and hole emission as a function of applied electric field. Both electrons and holes are emitted in a few picoseconds at high fields (e.g., 100 kV/cm) in low barrier (e.g., 20% Al) structures, and in hundreds of picoseconds at low fields (e.g., 20 kV/cm) in higher barrier (e.g., 40% Al) structures. Preliminary analysis suggests that the emission mechanism is thermionic rather than by tunneling, but the results are not well explained by conventional thermionic emission models.

    Journal Title

    Ieee Journal of Quantum Electronics

    Volume

    28

    Issue/Number

    10

    Publication Date

    1-1-1992

    Document Type

    Article

    Language

    English

    First Page

    2486

    Last Page

    2497

    WOS Identifier

    WOS:A1992JQ97500054

    ISSN

    0018-9197

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