Background limited performance of long wavelength infrared focal plane arrays fabricated from Type-Ⅱ InAs/GaSb M-structure superlattice

摘要

Recent advances in growth techniques, structure design and processing have lifted the performance of Type-Ⅱ InAs/GaSb superlattice photodetectors. The introduction of a M-structure design improved both the dark current and RoA of Type-Ⅱ photodiodes. This new structure combined with a thick absorbing region demonstrated background limited performance at 77K for a 300K background and a 2-π field of view. A focal plane array with a 9.6 μm 50% cutoff wavelength was fabricated with this design and characterized at 80K. The dark current of individual pixels was measured around 1.3 nA, 7 times lower than previous superlattice FPAs. This led to a higher dynamic range and longer integration times. The quantum efficiency of detectors without anti-reflective coating was 72%. The noise equivalent temperature difference reached 23 mK. The deposition of an anti-reflective coating improved the NEDT to 20 mK and the quantum efficiency to 89%.