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Proceedings Paper

High quantum efficiency long-wave infrared photodiodes using W- structured type-II superlattices
Author(s): E. H. Aifer; C. L. Canedy; J. G. Tischler; J. H. Warner; I. Vurgaftman; W. W Bewley; J. R. Meyer; E. M. Jackson; J. C. Kim; L. J. Whitman
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Paper Abstract

Recent improvements in material quality and design have led to large improvements in the quantum efficiency (QE) of long-wave infrared (LWIR) photodiodes based on W-structured type-II superlattices (WSL), which now have achieved external QE of up to 35% on an 11.3 μm cutoff photodiode operating at 80K. While single band and dual band WSLs have been demonstrated with cutoff wavelengths out to 17 μm, the initial devices also showed significant losses of photo-excited carriers resulting in QE levels of ≤ 10%. Here we describe recent results in which these losses have been dramatically reduced by modifying the WSL barrier layers to increase the mini-band width and improve the material properties. An additional 35-55% increase in QE also resulted from the use of semitransparent Te doped n-GaSb substrates that allowed for IR reflections off the backside from the Au plated chip carrier. A series of PIN photodiodes using the improved WSL, with intrinsic regions from 1 to 4 μm thick, were used to study minority carrier transport characteristics in the new structure. As a result of the improved design and material properties, the electron diffusion length in the undoped i-region, as determined from a theoretical fit to the thickness-dependent data, was 3.5 μm, allowing for much higher collection efficiency in PIN photodiodes with intrinsic regions up to 4 μm thick.

Paper Details

Date Published: 28 February 2006
PDF: 10 pages
Proc. SPIE 6127, Quantum Sensing and Nanophotonic Devices III, 61270T (28 February 2006); doi: 10.1117/12.660711
Show Author Affiliations
E. H. Aifer, Naval Research Lab. (United States)
C. L. Canedy, Naval Research Lab. (United States)
J. G. Tischler, Naval Research Lab. (United States)
J. H. Warner, Naval Research Lab. (United States)
I. Vurgaftman, Naval Research Lab. (United States)
W. W Bewley, Naval Research Lab. (United States)
J. R. Meyer, Naval Research Lab. (United States)
E. M. Jackson, SFA Inc. (United States)
J. C. Kim, Naval Research Lab. (United States)
L. J. Whitman, Naval Research Lab. (United States)

Published in SPIE Proceedings Vol. 6127:
Quantum Sensing and Nanophotonic Devices III
Manijeh Razeghi; Gail J. Brown, Editor(s)

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