SIMULTANEOUS MEASUREMENTS OF ELECTRON AND HOLE SWEEP-OUT FROM QUANTUM-WELLS AND MODELING OF PHOTOINDUCED FIELD SCREENING DYNAMICS

J A CAVAILLES, D A B MILLER, J E CUNNINGHAM, P L K WA, A MILLER

Research output: Contribution to journalArticle

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.

Original languageEnglish
Pages (from-to)2486-2497
Number of pages12
JournalIEEE Journal of Quantum Electronics
Volume28
Issue number10
Publication statusPublished - Oct 1992

Cite this

@article{ef4779bea6374082ac6b1ef4a9b580a0,
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{\%} 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.",
author = "CAVAILLES, {J A} and MILLER, {D A B} and CUNNINGHAM, {J E} and WA, {P L K} and A MILLER",
year = "1992",
month = "10",
language = "English",
volume = "28",
pages = "2486--2497",
journal = "IEEE Journal of Quantum Electronics",
issn = "0018-9197",
publisher = "IEEE",
number = "10",

}

SIMULTANEOUS MEASUREMENTS OF ELECTRON AND HOLE SWEEP-OUT FROM QUANTUM-WELLS AND MODELING OF PHOTOINDUCED FIELD SCREENING DYNAMICS. / CAVAILLES, J A ; MILLER, D A B ; CUNNINGHAM, J E ; WA, P L K ; MILLER, A .

In: IEEE Journal of Quantum Electronics, Vol. 28, No. 10, 10.1992, p. 2486-2497.

Research output: Contribution to journalArticle

TY - JOUR

T1 - SIMULTANEOUS MEASUREMENTS OF ELECTRON AND HOLE SWEEP-OUT FROM QUANTUM-WELLS AND MODELING OF PHOTOINDUCED FIELD SCREENING DYNAMICS

AU - CAVAILLES, J A

AU - MILLER, D A B

AU - CUNNINGHAM, J E

AU - WA, P L K

AU - MILLER, A

PY - 1992/10

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N2 - 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.

AB - 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.

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