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Proceedings Paper

Time-Resolved Photoluminescence Spectroscopy Of The Carrier Dynamics In GaAs/AlxGa1_xAs Quantum Wells
Author(s): Hans J. Polland; Jurgen Kuhl; Ernst O. Gobel
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Paper Abstract

Picosecond photoluminescence experiments at low temperature (6K) have been employed to study the trapping dynamics of photoexcited carriers in GaAs/AlGaAs single quantum wells for different shapes of the AlxGai_xAs confinement layers. We have obtained the following results by analyzing the spectral and temporal distribution of the photoluminescence after picosecond pulse excitation: Trapping efficiency is ==, 40% for a standard ungraded cladding layer (A10.3G1.7As with constant band gap and 5nm thick wells) but increases to ,-, 60% and 100% for samp es with a spatially parabolic or linear band gap profile of the confinement layers, respectively. Trapping times are appreciably shorter than the luminescence risetime which is between 60ps to 100ps. Thus carrier trapping does not impose severe limitations on the modulation speed of single quantum well devices up to frequencies in the order of 10GHz. Similar results are obtained for a well with a width of 1.2nm. Inhomogeneities in the carrier trapping mechanism due to well width fluctuations are not observed in our samples. In the second part we describe the photoluminescence properties of GaAs/A1,Gai_x As quantum wells (x=0.3) under the influence of electric fields perpendicular to the layers. We observe a drastic red shift and a concomitant strong increase of the electron-hole recombination lifetime for well widths > lOnm due to the quantum-confined Stark effect. At high fields (50-100kV/cm) field ionization due to tunneling leads to a decrease of both the photoluminescence yield and decay time, in accordance with a simple WKB theory

Paper Details

Date Published: 22 August 1988
PDF: 8 pages
Proc. SPIE 0942, Ultrafast Laser Probe Phenomena in Bulk and Microstructure Semiconductors II, (22 August 1988); doi: 10.1117/12.947219
Show Author Affiliations
Hans J. Polland, Max-Planck-Institut fur Festkorperforschung (Germany)
Jurgen Kuhl, Max-Planck-Institut fur Festkorperforschung (Germany)
Ernst O. Gobel, Philipps Universitat (Germany)

Published in SPIE Proceedings Vol. 0942:
Ultrafast Laser Probe Phenomena in Bulk and Microstructure Semiconductors II
Robert R. Alfano, Editor(s)

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