Optical and terahertz spectroscopy of doped GaAs/AlAs quantum wells

Gintaras Valušis, Julius Kavaliauskas, Bronislovas Čechavičius, Gene Krivaite, Dalius Seliuta, Ben Sherliker, Matthew Halsall, Paul Harrison, Suraj Khanna, Edmund Linfield

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Citation (Scopus)


We present comprehensive experimental study of p-type (Be) and n-type (Si) δ-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 μm wavelength due to intraband absorption of the bound holes, while increase in photocurrent in the structures below 80 μmn wavelength is caused by photothermal ionization of Be acceptors.

Original languageEnglish
Title of host publicationAdvanced Optical Materials, Technologies, and Devices
EditorsSteponas Ašmontas, Jonas Gradauskas
Number of pages12
ISBN (Print)0819467324, 9780819467324
Publication statusPublished - 25 Jan 2007
Externally publishedYes
EventAdvanced Optical Materials, Technologies, and Devices - Vilnius, Lithuania
Duration: 27 Aug 200630 Aug 2006

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceAdvanced Optical Materials, Technologies, and Devices


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