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Proceedings Paper

Modelling and measurement of bandgap behaviour in MWIR InAs/InAs(0.815)Sb(0.185) strained-layer superlattices
Author(s): Veronica Letka; James Keen; Adam Craig; Andrew R. J. Marshall
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Paper Abstract

InAs/InAs1-xSbx type-II strained-layer superlattices (SLS) are a structure with potential infrared detection applications, owing to its tunable bandgap and suppressed Auger recombination. A series of medium-wavelength infrared (MWIR) InAs/InAs0.815Sb0.185 SLS structures, grown as undoped absorption epilayers on GaAs, were fabricated using molecular beam epitaxy in order to study the dependence of the ground state transitions on temperature and superlattice period thickness. Photoluminescence peaks at 4 K were obtained with the use of a helium-cooled micro-PL system and an InSb detector, and temperature-dependent absorption spectra were measured in the range 77 K – 300 K on a Fourier Transform Infrared (FTIR) spectrometer, equipped with a 1370 K blackbody source and a DTGS detector. An nBn device sample with the absorber structure identical to one of the undoped samples was also grown and processed with the goal of measuring temperature-dependent spectral response. A model for superlattice band alignment was also devised, incorporating the Bir-Pikus transformation results for uniaxial and biaxial strain, and the Einstein oscillator model for bandgap temperature dependence. Absorption coefficients of several 1000 cm-1 throughout the entire MWIR range are found for all samples, and temperature dependence of the bandgaps is extracted and compared to the model. This and photoluminescence data also demonstrate bandgap shifts consistent with the different superlattice periods of the three samples.

Paper Details

Date Published: 6 October 2017
PDF: 7 pages
Proc. SPIE 10433, Electro-Optical and Infrared Systems: Technology and Applications XIV, 1043319 (6 October 2017); doi: 10.1117/12.2278733
Show Author Affiliations
Veronica Letka, Lancaster Univ. (United Kingdom)
James Keen, Lancaster Univ. (United Kingdom)
Adam Craig, Lancaster Univ. (United Kingdom)
Andrew R. J. Marshall, Lancaster Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 10433:
Electro-Optical and Infrared Systems: Technology and Applications XIV
David A. Huckridge; Reinhard Ebert; Helge Bürsing, Editor(s)

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