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Proceedings Paper

Defects and noise in Type-II superlattice infrared detectors
Author(s): Martin Walther; Andreas Wörl; Volker Daumer; Robert Rehm; Lutz Kirste; Frank Rutz; Johannes Schmitz
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Paper Abstract

To examine defects in InAs/GaSb type-II superlattices we investigated GaSb substrates and epitaxial InAs/GaSb layers by synchrotron white beam X-ray topography to characterize the distribution of threading dislocations. Those measurements are compared with wet chemical etch pit density measurements on GaSb substrates and InAs/GaSb type-II superlattices epitaxial layer structures. The technique uses a wet chemical etch process to decorate threading dislocations and an automated optical analyzing system for mapping the defect distribution. Dark current and noise measurements on processed InAs/GaSb type-II superlattice single element photo diodes reveal a generation-recombination limited dark current behavior without contributions by surface leakage currents for midwavelength infrared detectors. In the white noise part of the noise spectrum, the extracted diode noise closely matches the theoretically expected shot noise behavior. For diodes with an increased dark current in comparison to the dark current of generation-recombination limited material, the standard shot-noise model fails to describe the noise experimentally observed in the white part of the spectrum. Instead, we find that McIntyre’s noise model for avalanche multiplication processes fits the data quite well. We suggest that within high electric field domains localized around crystallographic defects, electrons initiate avalanche multiplication processes leading to increased dark current and excess noise.

Paper Details

Date Published: 11 June 2013
PDF: 9 pages
Proc. SPIE 8704, Infrared Technology and Applications XXXIX, 87040U (11 June 2013); doi: 10.1117/12.2015926
Show Author Affiliations
Martin Walther, Fraunhofer-Institut für Angewandte Festkörperphysik (Germany)
Andreas Wörl, Fraunhofer-Institut für Angewandte Festkörperphysik (Germany)
Volker Daumer, Fraunhofer-Institut für Angewandte Festkörperphysik (Germany)
Robert Rehm, Fraunhofer-Institut für Angewandte Festkörperphysik (Germany)
Lutz Kirste, Fraunhofer-Institut für Angewandte Festkörperphysik (Germany)
Frank Rutz, Fraunhofer-Institut für Angewandte Festkörperphysik (Germany)
Johannes Schmitz, Fraunhofer-Institut für Angewandte Festkörperphysik (Germany)


Published in SPIE Proceedings Vol. 8704:
Infrared Technology and Applications XXXIX
Bjørn F. Andresen; Gabor F. Fulop; Charles M. Hanson; Paul R. Norton; Patrick Robert, Editor(s)

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