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InAs/GaSb superlattice focal plane arrays for high-resolution thermal imaging

InAs/GaSb Übergitter-Detektorfeldmatrizen für hochauflösende Thermographie
: Rehm, R.; Walther, M.; Schmitz, J.; Fleißner, J.; Fuchs, F.; Ziegler, J.; Cabanski, W.


Opto-electronics review 14 (2006), No.1, pp.19-24
ISSN: 0033-2089
ISSN: 1230-3402
Journal Article
Fraunhofer IAF ()
IR-FPA; infrared; Infrarot; focal plane array; Detektormatrize; superlattice; Übergitter; quantum efficiency; Quanteneffizienz

The first fully operational mid-IR (3-5 µm) 256×256 IR-FPA camera system based on a type-II InAs/GaSb short-period superlattice showing an excellent noise equivalent temperature difference below 10 mK and a very uniform performance has been realized. We report on the development and fabrication of the detecor chip, i.e., epitaxy, processing technology and electro-optical characterization of fully integrated InAs/GaSb superlattice focal plane arrays. While the superlattice design employed for the first demonstrator camera yielded a quantum efficiency around 30%, a superlattice structure grown with a thicker active layer and an optimized V/III BEP ratio during growth of the InAs layers exhibits a significant increase in quantum efficiency. Quantitative responsivity measurements reveal a quantum efficiency of about 60% for InAs/GaSb superlattice focal plane arrays after implementing this design improvement.