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Proceedings Paper

Mid-infrared GaInSb quantum well laser structures: a comparison of their characterisation using photoluminescence, photo-modulated reflectance, and FTIR-based surface photovoltage spectroscopies
Author(s): Natasha E. Fox; A. Andreev; G. R. Nash; T. Ashley; T. J. C. Hosea
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Paper Abstract

We study four compressively strained GaInSb/AlGaInSb type I multi quantum-well (QW) laser structures grown on GaAs, with increasingly strained QWs, aimed at emitting at ~4μm. This wavelength region is highly important for applications such a free space communication, biomedical imaging and trace gas sensing. The structures are analysed using photoluminescence, photo-modulated reflectance and, at room temperature, using our novel, recently developed Fourier transform infrared surface photo-voltage spectroscopy technique (FTIR-SPS). Neither photoluminescence nor photo-modulated reflectance managed to give any characterisation information at room temperature or such detailed information even at low temperatures. However, FTIR-SPS clearly yielded a full set of transitions for all four samples including not only the barrier bandgap, but also the QW ground state transition, from which the device operating wavelengths can be inferred, and up to five excited state QW transitions. The full set of measured transition energies are then compared closely with those predicted by an 8-band k.p model which takes account of the band anisotropy and strain. There is generally a good agreement between the QW transitions predicted by the model and those measured experimentally, but there is also a strong indication that the current literature values for the AlGaInSb bandgap seem to be in considerable error for the present alloy compositions. The FTIR-SPS technique gives information of great importance when designing future devices to emit in this wavelength region.

Paper Details

Date Published: 10 September 2010
PDF: 10 pages
Proc. SPIE 7755, Nanophotonic Materials VII, 77550C (10 September 2010); doi: 10.1117/12.861159
Show Author Affiliations
Natasha E. Fox, Univ. of Surrey (United Kingdom)
A. Andreev, Univ. of Surrey (United Kingdom)
G. R. Nash, QinetiQ Ltd. (United Kingdom)
Univ. of Bristol (United Kingdom)
T. Ashley, QinetiQ Ltd. (United Kingdom)
T. J. C. Hosea, Univ. of Surrey (United Kingdom)

Published in SPIE Proceedings Vol. 7755:
Nanophotonic Materials VII
Stefano Cabrini; Taleb Mokari, Editor(s)

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