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Proceedings Paper

Optical and terahertz spectroscopy of doped GaAs/AlAs quantum wells
Author(s): Gintaras Valušis; Julius Kavaliauskas; Bronislovas Čechavičius; Genė Krivaitė; Dalius Seliuta; Ben Sherliker; Matthew Halsall; Paul Harrison; Suraj Khanna; Edmund Linfield
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Paper Abstract

We present comprehensive experimental study of p-type (Be) and n-type (Si) &dgr;-doped GaAs/AlAs multiple quantum wells (QWs) intended to be used as selective sensors/emitters in terahertz (THz) range. The structures of various designs and doping levels were studied via different optical-photoreflectance-, surface photovoltage- and differential surface photovoltage. spectroscopies and a THz photocurrent technique using as THz emission source either free electron- or optically-pumped molecular THz laser within 4.300 K range of temperatures. Analysis of Franz-Keldysh oscillations in photoreflectance spectra and line shapes of the differential surface photovoltage spectra enabled to estimate built-in electric fields and excitonic parameters for a large number of QW subbands. The experimental interband transition energies were compared with calculations performed within the envelope function approximation taking into account non-parabolicity of the energy bands. The dominant exciton line broadening mechanisms were revealed, and the interface roughness was evaluated from analysis of the dependence of exciton linewidth broadening on the QW width. Terahertz spectroscopic measurements in p-type structures have indicated strong absorption around 55 &mgr;m wavelength due to intraband absorption of the bound holes, while increase in photocurrent in the structures below 80 &mgr;m wavelength is caused by photothermal ionization of Be acceptors.

Paper Details

Date Published: 25 January 2007
PDF: 12 pages
Proc. SPIE 6596, Advanced Optical Materials, Technologies, and Devices, 65960L (25 January 2007); doi: 10.1117/12.726406
Show Author Affiliations
Gintaras Valušis, Semiconductor Physics Institute (Lithuania)
Gediminas Technical Univ. of Vilnius (Lithuania)
Julius Kavaliauskas, Semiconductor Physics Institute (Lithuania)
Bronislovas Čechavičius, Semiconductor Physics Institute (Lithuania)
Genė Krivaitė, Semiconductor Physics Institute (Lithuania)
Gediminas Technical Univ. of Vilnius (Lithuania)
Dalius Seliuta, Semiconductor Physics Institute (Lithuania)
Gediminas Technical Univ. of Vilnius (Lithuania)
Ben Sherliker, Univ. of Manchester (United Kingdom)
Matthew Halsall, Univ. of Manchester (United Kingdom)
Paul Harrison, Univ. of Leeds (United Kingdom)
Suraj Khanna, Univ. of Leeds (United Kingdom)
Edmund Linfield, Univ. of Leeds (United Kingdom)

Published in SPIE Proceedings Vol. 6596:
Advanced Optical Materials, Technologies, and Devices
Steponas Ašmontas; Jonas Gradauskas, Editor(s)

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