An approach for the passivation of photodiodes based on compounds of the InAs∕GaSb∕AlSb materials family is presented. The passivation is realized by the overgrowth of patterned mesa devices with a quaternary AlxGa1−xAsySb1−y layer, lattice matched to the GaSb substrate. Proof of concept is demonstrated on infrared photodiodes based on InAs∕(GaIn)Sb superlattices with 10μm cutoff wavelength operating at 77 K where suppression of surface leakage currents is observed.

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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.