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Proceedings Paper

Type-II superlattice materials for mid-infrared detection
Author(s): Gail J. Brown; Heather Haugan; Frank Szmulowicz; Krishnamur Mahalingam; L. Grazulis; Shanee Houston
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Paper Abstract

Type-II superlattices composed of alternating thin layers of InAs and GaSb, have been shown to be a highly flexible infrared materials system in which the energy band gap can be adjusted anywhere between 360 meV and 40 meV. These superlattices (SLs) are the III-V equivalent to the well established HgxCd1-xTe alloys used for infrared detection in the short, mid and long wavelength bands of the infrared spectrum. There are many possible designs for these superlattices that will produce the same narrow band gap by adjusting individual layer thicknesses and interface composition. Systematic growth and characterization studies were performed to determine optimum superlattice designs suitable for infrared detection in the 3 to 5 μm wavelength band. For these studies the individual layer thicknesses were less than 35Å. The effects of adding different thickness InSb-like interfaces were also studied. Through precision molecular beam epitaxy, design changes as small as 3Å to the SL layers could be studied. Significant changes were observed in the infrared photoresponse spectra of the various SL samples. The infrared properties of the various designs of these type-II superlattices were modeled using an 8-band Envelope Function Approximation. The infrared photoresponse spectra, combined with quantum mechanical modeling of predicted absorption spectra, were a key factor in the design optimization of the InAs/GaSb superlattices with band gaps in the range of 200 to 360 meV.

Paper Details

Date Published: 25 March 2005
PDF: 10 pages
Proc. SPIE 5732, Quantum Sensing and Nanophotonic Devices II, (25 March 2005); doi: 10.1117/12.597076
Show Author Affiliations
Gail J. Brown, Air Force Research Lab. (United States)
Heather Haugan, Air Force Research Lab. (United States)
Frank Szmulowicz, Air Force Research Lab. (United States)
Krishnamur Mahalingam, Air Force Research Lab. (United States)
L. Grazulis, Air Force Research Lab. (United States)
Shanee Houston, Air Force Research Lab. (United States)

Published in SPIE Proceedings Vol. 5732:
Quantum Sensing and Nanophotonic Devices II
Manijeh Razeghi; Gail J. Brown, Editor(s)

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