Title

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

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% AI) 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. © 1992 IEEE.

Publication Date

1-1-1992

Publication Title

IEEE Journal of Quantum Electronics

Volume

28

Issue

10

Number of Pages

2486-2497

Document Type

Article

Identifier

scopus

Personal Identifier

scopus

DOI Link

https://doi.org/10.1109/3.159555

Socpus ID

0026941016 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/0026941016

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