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Growth of InAs/GaSb short-period superlattices for high-resolution mid-wavelength infrared focal plane array detectors

Wachstum von kurz-periodigen InAs/GaSb Übergitter für hochauflösende Bildfeldmatrix-Detektoren im mittleren Infrarot-Spektralbereich
: Walther, M.; Schmitz, J.; Rehm, R.; Kopta, S.; Fuchs, F.; Fleißner, J.; Cabanski, W.; Ziegler, J.


Jones, T.S.:
MBE XIII, 13th International Conference on Molecular Beam Epitaxy 2004 : Edinburg, UK, 22 - 27 August 2004
Amsterdam: Elsevier, 2005 (Journal of crystal growth 278.2005, Nr.1/4)
International Conference on Molecular Beam Epitaxy (MBE) <13, 2004, Edinburgh>
Conference Paper, Journal Article
Fraunhofer IAF ()
MBE; molecular beam epitaxy; Molekularstrahlepitaxie; superlattice; Übergitter; antimonide; infrared; Infrarot; device; Bauelement

InAs/GaSb short-period superlattices (SLs) with a broken gap type-II band alignment are investigated for the fabrication of photovoltaic pin-photodetectors on GaSb substrates. The structures were grown by molecular beam epitaxy using valved cracker cells for arsenic and antimony. Effective bandgap and strain in the SL were adjusted by varying the thickness of the InAs and GaSb layers in the SL and the controlled formation of InSb-like or GaAs-like bonds at the interfaces. MBE growth conditions were investigated and optimized in order to achieve good morphological, electrical and optical properties. IR-photodiodes with a cut-off wavelength of 5.4 µm reveal quantum efficiencies around 30% and detectivity values exceeding 10(exp 13) Jones at 77 K. A focal plane array camera with 256 x 256 detector elements and 40 µm pitch based on InAs/GaSb short-period SLs was fabricated for the first time. The camera system reveals an excellent thermal resolution with a noise equivalent temperature difference below 12 mK for an integration time of 5 ms using f/2 optics. The detector performance, comparable with state of the art mercury-cadmium-telluride IR detectors, makes this material system very interesting for the fabrication of advanced thermal imaging systems.