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256 x 256 focal plane array midwavelength infrared camera based on InAs/GaSb short-period superlattices

256 X 256 Bildfeldmatrix-Kamera für das mittlere Infrarot auf InAs/GaSb Übergitter
: Walther, M.; Rehm, R.; Fuchs, F.; Schmitz, J.; Fleißner, J.; Cabanski, W.; Eich, D.; Finck, M.; Rode, W.; Wendler, J.; Wollrab, R.; Ziegler, J.

Institute of Electrical and Electronics Engineers -IEEE-:
U.S. Workshop on the Physics and Chemistry of II-VI Materials 2004. Special issue : Was held in Chicago, Illinois on October 5 til 7
Warrendale/Pa.: TMS, 2005 (Journal of electronic materials 34.2005,6)
US Workshop on the Physics and Chemistry of II-VI Materials <23, 2004, Chicago/Ill.>
Conference Paper, Journal Article
Fraunhofer IAF ()
InAs/GaSb; superlattice; Übergitter; focal plane array; Bildfeldmatrix; infrared; camera; Infrarotkamera

An infrared camera based on a 256 x 256 focal plane array (FPA) for the second atmospheric window (3-5 µm) has been realized for the first time with InAs/GaSb short period superlattices (SLs). The SL detector structure with a broken gap type-II band alignment was grown by molecular beam epitaxy on GaSb substrates. Effective bandgap and strain in the superlattice were adjusted by varying the thickness of the InAs and GaSb layers and the controlled formation of InSb-like bonds at the interfaces. The FPAs were processed in a full wafer process using optical lithography, chemical-assisted ion beam etching, and conventional metallization technology. The FPAs were flip-chip bonded using indium solder bumps with a read-out integrated circuit and mounted into an integrated detector cooler assembly. The FPAs with a cut-off wavelength of 5.4 µm exhibit quantum efficiencies of 30% and detectivity values exceeding 10(exp 13) Jones at T = 77 K. A noise equivalent temperature difference (NETD) of 11.1 mK was measured for an integration time of 5 ms using f/2 optics. The NETD scales inversely proportional to the square root of the integration time between 5 ms and 1 ms, revealing background limited performance. Excellent thermal images with low NETD values and a very good modulation transfer function demonstrate the high potential of this material system for the fabrication of future thermal imaging systems.